diff --git a/apps/plugins/puzzles/src/Buildscr b/apps/plugins/puzzles/src/Buildscr
index c72084477b..b8a585b43e 100644
--- a/apps/plugins/puzzles/src/Buildscr
+++ b/apps/plugins/puzzles/src/Buildscr
@@ -54,24 +54,30 @@ in puzzles do make -f Makefile.doc clean
 in puzzles do make -f Makefile.doc # build help files for installer
 in puzzles do mason.pl --args '{"version":"$(Version)","descfile":"gamedesc.txt"}' winwix.mc > puzzles.wxs
 in puzzles do perl winiss.pl $(Version) gamedesc.txt > puzzles.iss
-delegate windows
-  # FIXME: Cygwin alternative?
-  in puzzles with visualstudio do/win nmake -f Makefile.vc clean
-  in puzzles with visualstudio do/win nmake -f Makefile.vc VER=-DVER=$(Version)
+ifneq "$(VISUAL_STUDIO)" "yes" then
+  in puzzles with clangcl64 do Platform=x64 make -f Makefile.clangcl clean
+  in puzzles with clangcl64 do Platform=x64 make -f Makefile.clangcl VER=-DVER=$(Version)
   # Code-sign the binaries, if the local bob config provides a script
   # to do so. We assume here that the script accepts an -i option to
   # provide a 'more info' URL, and an optional -n option to provide a
   # program name, and that it can take multiple .exe filename
   # arguments and sign them all in place.
-  ifneq "$(winsigncode)" "" in puzzles do $(winsigncode) -i https://www.chiark.greenend.org.uk/~sgtatham/puzzles/ *.exe
+  ifneq "$(cross_winsigncode)" "" in puzzles do $(cross_winsigncode) -i https://www.chiark.greenend.org.uk/~sgtatham/puzzles/ *.exe
   # Build installers.
-  in puzzles with wix do/win candle puzzles.wxs && light -ext WixUIExtension -sval puzzles.wixobj
-  in puzzles with innosetup do/win iscc puzzles.iss
-  ifneq "$(winsigncode)" "" in puzzles do $(winsigncode) -i https://www.chiark.greenend.org.uk/~sgtatham/puzzles/ -n "Simon Tatham's Portable Puzzle Collection Installer" puzzles.msi Output/installer.exe
-  return puzzles/*.exe
-  return puzzles/Output/installer.exe
-  return puzzles/puzzles.msi
-enddelegate
+  in puzzles with wixonlinux do candle -arch x64 puzzles.wxs && light -ext WixUIExtension -sval puzzles.wixobj
+  ifneq "$(cross_winsigncode)" "" in puzzles do $(cross_winsigncode) -i https://www.chiark.greenend.org.uk/~sgtatham/puzzles/ -n "Simon Tatham's Portable Puzzle Collection Installer" puzzles.msi
+else
+  delegate windows
+    in puzzles with visualstudio do/win nmake -f Makefile.vc clean
+    in puzzles with visualstudio do/win nmake -f Makefile.vc VER=-DVER=$(Version)
+    ifneq "$(winsigncode)" "" in puzzles do $(winsigncode) -i https://www.chiark.greenend.org.uk/~sgtatham/puzzles/ *.exe
+    # Build installers.
+    in puzzles with wix do/win candle puzzles.wxs && light -ext WixUIExtension -sval puzzles.wixobj
+    in puzzles with innosetup do/win iscc puzzles.iss
+    return puzzles/*.exe
+    return puzzles/puzzles.msi
+  enddelegate
+endif
 in puzzles do chmod +x *.exe
 
 # Build the Pocket PC binaries and CAB.
@@ -152,13 +158,22 @@ delegate emscripten
   return puzzles/js/*.js
 enddelegate
 
+# Build a set of wrapping HTML pages for easy testing of the
+# Javascript puzzles. These aren't quite the same as the versions that
+# will go on my live website, because those ones will substitute in a
+# different footer, and not have to link to the .js files with the
+# ../js/ prefix. But these ones should be good enough to just open
+# using a file:// URL in a browser after running a build, and make
+# sure the main functionality works.
+in puzzles do mkdir jstest
+in puzzles/jstest do ../html/jspage.pl --jspath=../js/ /dev/null ../html/*.html
+
 # Set up .htaccess containing a redirect for the archive filename.
 in puzzles do echo "AddType application/octet-stream .chm" > .htaccess
 in puzzles do echo "AddType application/octet-stream .hlp" >> .htaccess
 in puzzles do echo "AddType application/octet-stream .cnt" >> .htaccess
 in . do set -- puzzles*.tar.gz; echo RedirectMatch temp '(.*/)'puzzles.tar.gz '$$1'"$$1" >> puzzles/.htaccess
 in puzzles do echo RedirectMatch temp '(.*/)'puzzles-installer.msi '$$1'puzzles-$(Version)-installer.msi >> .htaccess
-in puzzles do echo RedirectMatch temp '(.*/)'puzzles-installer.exe '$$1'puzzles-$(Version)-installer.exe >> .htaccess
 
 # Phew, we're done. Deliver everything!
 deliver puzzles/icons/*-web.png $@
@@ -172,9 +187,9 @@ deliver puzzles/puzzles.hlp $@
 deliver puzzles/puzzles.cnt $@
 deliver puzzles/puzzles.zip $@
 deliver puzzles/puzzles.msi puzzles-$(Version)-installer.msi
-deliver puzzles/Output/installer.exe puzzles-$(Version)-installer.exe
 deliver puzzles/*.jar java/$@
 deliver puzzles/js/*.js js/$@
+deliver puzzles/jstest/*.html jstest/$@
 deliver puzzles/html/*.html html/$@
 deliver puzzles/html/*.pl html/$@
 deliver puzzles/wwwspans.html $@
diff --git a/apps/plugins/puzzles/src/PuzzleApplet.java b/apps/plugins/puzzles/src/PuzzleApplet.java
index 512aede580..8455734dd1 100644
--- a/apps/plugins/puzzles/src/PuzzleApplet.java
+++ b/apps/plugins/puzzles/src/PuzzleApplet.java
@@ -61,19 +61,19 @@ public class PuzzleApplet extends JApplet implements Runtime.CallJavaCB {
             JMenuBar menubar = new JMenuBar();
             JMenu jm;
             menubar.add(jm = new JMenu("Game"));
-            addMenuItemWithKey(jm, "New", 'n');
+            addMenuItemCallback(jm, "New", "jcallback_newgame_event");
             addMenuItemCallback(jm, "Restart", "jcallback_restart_event");
             addMenuItemCallback(jm, "Specific...", "jcallback_config_event", CFG_DESC);
             addMenuItemCallback(jm, "Random Seed...", "jcallback_config_event", CFG_SEED);
             jm.addSeparator();
-            addMenuItemWithKey(jm, "Undo", 'u');
-            addMenuItemWithKey(jm, "Redo", 'r');
+            addMenuItemCallback(jm, "Undo", "jcallback_undo_event");
+            addMenuItemCallback(jm, "Redo", "jcallback_redo_event");
             jm.addSeparator();
             solveCommand = addMenuItemCallback(jm, "Solve", "jcallback_solve_event");
             solveCommand.setEnabled(false);
             if (mainWindow != null) {
                 jm.addSeparator();
-                addMenuItemWithKey(jm, "Exit", 'q');
+                addMenuItemCallback(jm, "Exit", "jcallback_quit_event");
             }
             menubar.add(typeMenu = new JMenu("Type"));
             typeMenu.setVisible(false);
@@ -126,7 +126,12 @@ public class PuzzleApplet extends JApplet implements Runtime.CallJavaCB {
                     }
                 }
                 public void keyTyped(KeyEvent e) {
-                    runtimeCall("jcallback_key_event", new int[] {0, 0, e.getKeyChar()});
+                    int key = e.getKeyChar();
+                    if (key == 26 && e.isShiftDown() && e.isControlDown()) {
+                        runtimeCall("jcallback_redo_event", new int[0]);
+                        return;
+                    }
+                    runtimeCall("jcallback_key_event", new int[] {0, 0, key});
                 }
             });
             pp.addMouseListener(new MouseAdapter() {
@@ -217,10 +222,6 @@ public class PuzzleApplet extends JApplet implements Runtime.CallJavaCB {
         runtimeCall("jcallback_resize", new int[] {pp.getWidth(), pp.getHeight()});
     }
 
-    private void addMenuItemWithKey(JMenu jm, String name, int key) {
-        addMenuItemCallback(jm, name, "jcallback_menu_key_event", key);
-    }
-
     private JMenuItem addMenuItemCallback(JMenu jm, String name, final String callback, final int arg) {
         return addMenuItemCallback(jm, name, callback, new int[] {arg}, false);
     }
diff --git a/apps/plugins/puzzles/src/Recipe b/apps/plugins/puzzles/src/Recipe
index ba8317f51a..3b57ef5e54 100644
--- a/apps/plugins/puzzles/src/Recipe
+++ b/apps/plugins/puzzles/src/Recipe
@@ -17,6 +17,7 @@
 !makefile gnustep Makefile.gnustep
 !makefile nestedvm Makefile.nestedvm
 !makefile emcc Makefile.emcc
+!makefile clangcl Makefile.clangcl
 
 !srcdir icons/
 
diff --git a/apps/plugins/puzzles/src/chm.but b/apps/plugins/puzzles/src/chm.but
deleted file mode 100644
index e0237044e4..0000000000
--- a/apps/plugins/puzzles/src/chm.but
+++ /dev/null
@@ -1,21 +0,0 @@
-\# File containing the magic HTML configuration directives to create
-\# an MS HTML Help project. We put this on the end of the Puzzles
-\# docs build command line to build the HHP and friends.
-
-\cfg{html-leaf-level}{infinite}
-\cfg{html-leaf-contains-contents}{false}
-\cfg{html-suppress-navlinks}{true}
-\cfg{html-suppress-address}{true}
-
-\cfg{html-contents-filename}{index.html}
-\cfg{html-template-filename}{%k.html}
-\cfg{html-template-fragment}{%k}
-
-\cfg{html-mshtmlhelp-chm}{puzzles.chm}
-\cfg{html-mshtmlhelp-project}{puzzles.hhp}
-\cfg{html-mshtmlhelp-contents}{puzzles.hhc}
-\cfg{html-mshtmlhelp-index}{puzzles.hhk}
-
-\cfg{html-body-end}{}
-
-\cfg{html-head-end}{<link rel="stylesheet" type="text/css" href="chm.css">}
diff --git a/apps/plugins/puzzles/src/devel.but b/apps/plugins/puzzles/src/devel.but
index a38fdda5d0..25a6c62dfa 100644
--- a/apps/plugins/puzzles/src/devel.but
+++ b/apps/plugins/puzzles/src/devel.but
@@ -1928,6 +1928,9 @@ Indeed, even horizontal or vertical lines may be anti-aliased.
 
 This function may be used for both drawing and printing.
 
+If the specified thickness is less than 1.0, 1.0 is used.
+This ensures that thin lines are visible even at small scales.
+
 \S{drawing-draw-text} \cw{draw_text()}
 
 \c void draw_text(drawing *dr, int x, int y, int fonttype,
diff --git a/apps/plugins/puzzles/src/drawing.c b/apps/plugins/puzzles/src/drawing.c
index 7f4a6cf674..a10a7f06d6 100644
--- a/apps/plugins/puzzles/src/drawing.c
+++ b/apps/plugins/puzzles/src/drawing.c
@@ -90,6 +90,8 @@ void draw_line(drawing *dr, int x1, int y1, int x2, int y2, int colour)
 void draw_thick_line(drawing *dr, float thickness,
 		     float x1, float y1, float x2, float y2, int colour)
 {
+    if (thickness < 1.0)
+        thickness = 1.0;
     if (dr->api->draw_thick_line) {
 	dr->api->draw_thick_line(dr->handle, thickness,
 				 x1, y1, x2, y2, colour);
diff --git a/apps/plugins/puzzles/src/emcc.c b/apps/plugins/puzzles/src/emcc.c
index ca033cbd47..23ab333f5d 100644
--- a/apps/plugins/puzzles/src/emcc.c
+++ b/apps/plugins/puzzles/src/emcc.c
@@ -310,6 +310,8 @@ void key(int keycode, int charcode, const char *key, const char *chr,
         keyevent = MOD_NUM_KEYPAD | '7';
     } else if (!strnullcmp(key, "PageUp") || keycode==33) {
         keyevent = MOD_NUM_KEYPAD | '9';
+    } else if (shift && ctrl && (keycode & 0x1F) == 26) {
+        keyevent = UI_REDO;
     } else if (chr && chr[0] && !chr[1]) {
         keyevent = chr[0] & 0xFF;
     } else if (keycode >= 96 && keycode < 106) {
@@ -323,10 +325,10 @@ void key(int keycode, int charcode, const char *key, const char *chr,
     }
 
     if (keyevent >= 0) {
-        if (shift && keyevent >= 0x100)
+        if (shift && (keyevent >= 0x100 && !IS_UI_FAKE_KEY(keyevent)))
             keyevent |= MOD_SHFT;
 
-        if (ctrl) {
+        if (ctrl && !IS_UI_FAKE_KEY(keyevent)) {
             if (keyevent >= 0x100)
                 keyevent |= MOD_CTRL;
             else
@@ -725,7 +727,7 @@ void command(int n)
         update_undo_redo();
         break;
       case 5:                          /* New Game */
-        midend_process_key(me, 0, 0, 'n');
+        midend_process_key(me, 0, 0, UI_NEWGAME);
         update_undo_redo();
         js_focus_canvas();
         break;
@@ -735,12 +737,12 @@ void command(int n)
         js_focus_canvas();
         break;
       case 7:                          /* Undo */
-        midend_process_key(me, 0, 0, 'u');
+        midend_process_key(me, 0, 0, UI_UNDO);
         update_undo_redo();
         js_focus_canvas();
         break;
       case 8:                          /* Redo */
-        midend_process_key(me, 0, 0, 'r');
+        midend_process_key(me, 0, 0, UI_REDO);
         update_undo_redo();
         js_focus_canvas();
         break;
@@ -756,6 +758,83 @@ void command(int n)
     }
 }
 
+/* ----------------------------------------------------------------------
+ * Called from JS to prepare a save-game file, and free one after it's
+ * been used.
+ */
+
+struct savefile_write_ctx {
+    char *buffer;
+    size_t pos;
+};
+
+static void savefile_write(void *vctx, void *buf, int len)
+{
+    struct savefile_write_ctx *ctx = (struct savefile_write_ctx *)vctx;
+    if (ctx->buffer)
+        memcpy(ctx->buffer + ctx->pos, buf, len);
+    ctx->pos += len;
+}
+
+char *get_save_file(void)
+{
+    struct savefile_write_ctx ctx;
+    size_t size;
+
+    /* First pass, to count up the size */
+    ctx.buffer = NULL;
+    ctx.pos = 0;
+    midend_serialise(me, savefile_write, &ctx);
+    size = ctx.pos;
+
+    /* Second pass, to actually write out the data */
+    ctx.buffer = snewn(size, char);
+    ctx.pos = 0;
+    midend_serialise(me, savefile_write, &ctx);
+    assert(ctx.pos == size);
+
+    return ctx.buffer;
+}
+
+void free_save_file(char *buffer)
+{
+    sfree(buffer);
+}
+
+struct savefile_read_ctx {
+    const char *buffer;
+    int len_remaining;
+};
+
+static int savefile_read(void *vctx, void *buf, int len)
+{
+    struct savefile_read_ctx *ctx = (struct savefile_read_ctx *)vctx;
+    if (ctx->len_remaining < len)
+        return FALSE;
+    memcpy(buf, ctx->buffer, len);
+    ctx->len_remaining -= len;
+    ctx->buffer += len;
+    return TRUE;
+}
+
+void load_game(const char *buffer, int len)
+{
+    struct savefile_read_ctx ctx;
+    const char *err;
+
+    ctx.buffer = buffer;
+    ctx.len_remaining = len;
+    err = midend_deserialise(me, savefile_read, &ctx);
+
+    if (err) {
+        js_error_box(err);
+    } else {
+        select_appropriate_preset();
+        resize();
+        midend_redraw(me);
+    }
+}
+
 /* ----------------------------------------------------------------------
  * Setup function called at page load time. It's called main() because
  * that's the most convenient thing in Emscripten, but it's not main()
diff --git a/apps/plugins/puzzles/src/emcclib.js b/apps/plugins/puzzles/src/emcclib.js
index cd8876e76d..907dc19995 100644
--- a/apps/plugins/puzzles/src/emcclib.js
+++ b/apps/plugins/puzzles/src/emcclib.js
@@ -108,7 +108,6 @@ mergeInto(LibraryManager.library, {
         item.appendChild(tick);
         item.appendChild(document.createTextNode(name));
         var submenu = document.createElement("ul");
-        submenu.className = "left";
         item.appendChild(submenu);
         gametypesubmenus[menuid].appendChild(item);
         var toret = gametypesubmenus.length;
@@ -575,38 +574,7 @@ mergeInto(LibraryManager.library, {
      * overlay on top of the rest of the puzzle web page.
      */
     js_dialog_init: function(titletext) {
-        // Create an overlay on the page which darkens everything
-        // beneath it.
-        dlg_dimmer = document.createElement("div");
-        dlg_dimmer.style.width = "100%";
-        dlg_dimmer.style.height = "100%";
-        dlg_dimmer.style.background = '#000000';
-        dlg_dimmer.style.position = 'fixed';
-        dlg_dimmer.style.opacity = 0.3;
-        dlg_dimmer.style.top = dlg_dimmer.style.left = 0;
-        dlg_dimmer.style["z-index"] = 99;
-
-        // Now create a form which sits on top of that in turn.
-        dlg_form = document.createElement("form");
-        dlg_form.style.width = (window.innerWidth * 2 / 3) + "px";
-        dlg_form.style.opacity = 1;
-        dlg_form.style.background = '#ffffff';
-        dlg_form.style.color = '#000000';
-        dlg_form.style.position = 'absolute';
-        dlg_form.style.border = "2px solid black";
-        dlg_form.style.padding = "20px";
-        dlg_form.style.top = (window.innerHeight / 10) + "px";
-        dlg_form.style.left = (window.innerWidth / 6) + "px";
-        dlg_form.style["z-index"] = 100;
-
-        var title = document.createElement("p");
-        title.style.marginTop = "0px";
-        title.appendChild(document.createTextNode
-                          (Pointer_stringify(titletext)));
-        dlg_form.appendChild(title);
-
-        dlg_return_funcs = [];
-        dlg_next_id = 0;
+        dialog_init(Pointer_stringify(titletext));
     },
 
     /*
@@ -701,29 +669,13 @@ mergeInto(LibraryManager.library, {
      * everything else on the page.
      */
     js_dialog_launch: function() {
-        // Put in the OK and Cancel buttons at the bottom.
-        var button;
-
-        button = document.createElement("input");
-        button.type = "button";
-        button.value = "OK";
-        button.onclick = function(event) {
+        dialog_launch(function(event) {
             for (var i in dlg_return_funcs)
                 dlg_return_funcs[i]();
-            command(3);
-        }
-        dlg_form.appendChild(button);
-
-        button = document.createElement("input");
-        button.type = "button";
-        button.value = "Cancel";
-        button.onclick = function(event) {
-            command(4);
-        }
-        dlg_form.appendChild(button);
-
-        document.body.appendChild(dlg_dimmer);
-        document.body.appendChild(dlg_form);
+            command(3);         // OK
+        }, function(event) {
+            command(4);         // Cancel
+        });
     },
 
     /*
@@ -733,10 +685,7 @@ mergeInto(LibraryManager.library, {
      * associated with it.
      */
     js_dialog_cleanup: function() {
-        document.body.removeChild(dlg_dimmer);
-        document.body.removeChild(dlg_form);
-        dlg_dimmer = dlg_form = null;
-        onscreen_canvas.focus();
+        dialog_cleanup();
     },
 
     /*
diff --git a/apps/plugins/puzzles/src/emccpre.js b/apps/plugins/puzzles/src/emccpre.js
index d715858883..5082555617 100644
--- a/apps/plugins/puzzles/src/emccpre.js
+++ b/apps/plugins/puzzles/src/emccpre.js
@@ -129,6 +129,72 @@ function disable_menu_item(item, disabledFlag) {
         item.className = "";
 }
 
+// Dialog-box functions called from both C and JS.
+function dialog_init(titletext) {
+    // Create an overlay on the page which darkens everything
+    // beneath it.
+    dlg_dimmer = document.createElement("div");
+    dlg_dimmer.style.width = "100%";
+    dlg_dimmer.style.height = "100%";
+    dlg_dimmer.style.background = '#000000';
+    dlg_dimmer.style.position = 'fixed';
+    dlg_dimmer.style.opacity = 0.3;
+    dlg_dimmer.style.top = dlg_dimmer.style.left = 0;
+    dlg_dimmer.style["z-index"] = 99;
+
+    // Now create a form which sits on top of that in turn.
+    dlg_form = document.createElement("form");
+    dlg_form.style.width = (window.innerWidth * 2 / 3) + "px";
+    dlg_form.style.opacity = 1;
+    dlg_form.style.background = '#ffffff';
+    dlg_form.style.color = '#000000';
+    dlg_form.style.position = 'absolute';
+    dlg_form.style.border = "2px solid black";
+    dlg_form.style.padding = "20px";
+    dlg_form.style.top = (window.innerHeight / 10) + "px";
+    dlg_form.style.left = (window.innerWidth / 6) + "px";
+    dlg_form.style["z-index"] = 100;
+
+    var title = document.createElement("p");
+    title.style.marginTop = "0px";
+    title.appendChild(document.createTextNode(titletext));
+    dlg_form.appendChild(title);
+
+    dlg_return_funcs = [];
+    dlg_next_id = 0;
+}
+
+function dialog_launch(ok_function, cancel_function) {
+    // Put in the OK and Cancel buttons at the bottom.
+    var button;
+
+    if (ok_function) {
+        button = document.createElement("input");
+        button.type = "button";
+        button.value = "OK";
+        button.onclick = ok_function;
+        dlg_form.appendChild(button);
+    }
+
+    if (cancel_function) {
+        button = document.createElement("input");
+        button.type = "button";
+        button.value = "Cancel";
+        button.onclick = cancel_function;
+        dlg_form.appendChild(button);
+    }
+
+    document.body.appendChild(dlg_dimmer);
+    document.body.appendChild(dlg_form);
+}
+
+function dialog_cleanup() {
+    document.body.removeChild(dlg_dimmer);
+    document.body.removeChild(dlg_form);
+    dlg_dimmer = dlg_form = null;
+    onscreen_canvas.focus();
+}
+
 // Init function called from body.onload.
 function initPuzzle() {
     // Construct the off-screen canvas used for double buffering.
@@ -230,6 +296,58 @@ function initPuzzle() {
             command(9);
     };
 
+    // 'number' is used for C pointers
+    get_save_file = Module.cwrap('get_save_file', 'number', []);
+    free_save_file = Module.cwrap('free_save_file', 'void', ['number']);
+    load_game = Module.cwrap('load_game', 'void', ['string', 'number']);
+
+    document.getElementById("save").onclick = function(event) {
+        if (dlg_dimmer === null) {
+            var savefile_ptr = get_save_file();
+            var savefile_text = Pointer_stringify(savefile_ptr);
+            free_save_file(savefile_ptr);
+            dialog_init("Download saved-game file");
+            dlg_form.appendChild(document.createTextNode(
+                "Click to download the "));
+            var a = document.createElement("a");
+            a.download = "puzzle.sav";
+            a.href = "data:application/octet-stream," +
+                encodeURIComponent(savefile_text);
+            a.appendChild(document.createTextNode("saved-game file"));
+            dlg_form.appendChild(a);
+            dlg_form.appendChild(document.createTextNode("."));
+            dlg_form.appendChild(document.createElement("br"));
+            dialog_launch(function(event) {
+                dialog_cleanup();
+            });
+        }
+    };
+
+    document.getElementById("load").onclick = function(event) {
+        if (dlg_dimmer === null) {
+            dialog_init("Upload saved-game file");
+            var input = document.createElement("input");
+            input.type = "file";
+            input.multiple = false;
+            dlg_form.appendChild(input);
+            dlg_form.appendChild(document.createElement("br"));
+            dialog_launch(function(event) {
+                if (input.files.length == 1) {
+                    var file = input.files.item(0);
+                    var reader = new FileReader();
+                    reader.addEventListener("loadend", function() {
+                        var string = reader.result;
+                        load_game(string, string.length);
+                    });
+                    reader.readAsBinaryString(file);
+                }
+                dialog_cleanup();
+            }, function(event) {
+                dialog_cleanup();
+            });
+        }
+    };
+
     gametypelist = document.getElementById("gametype");
     gametypesubmenus.push(gametypelist);
 
diff --git a/apps/plugins/puzzles/src/emccx.json b/apps/plugins/puzzles/src/emccx.json
index e03f7e25c7..bdab346d79 100644
--- a/apps/plugins/puzzles/src/emccx.json
+++ b/apps/plugins/puzzles/src/emccx.json
@@ -18,6 +18,10 @@
     '_timer_callback',
     // Callback from button presses in the UI outside the canvas
     '_command',
+    // Game-saving and game-loading functions
+    '_get_save_file',
+    '_free_save_file',
+    '_load_game',
     // Callbacks to return values from dialog boxes
     '_dlg_return_sval',
     '_dlg_return_ival',
diff --git a/apps/plugins/puzzles/src/gtk.c b/apps/plugins/puzzles/src/gtk.c
index c5e3d1c997..c212522957 100644
--- a/apps/plugins/puzzles/src/gtk.c
+++ b/apps/plugins/puzzles/src/gtk.c
@@ -140,7 +140,7 @@ struct font {
  */
 struct frontend {
     GtkWidget *window;
-    GtkAccelGroup *accelgroup;
+    GtkAccelGroup *dummy_accelgroup;
     GtkWidget *area;
     GtkWidget *statusbar;
     GtkWidget *menubar;
@@ -1160,16 +1160,6 @@ static gint key_event(GtkWidget *widget, GdkEventKey *event, gpointer data)
     if (!backing_store_ok(fe))
         return TRUE;
 
-#if !GTK_CHECK_VERSION(2,0,0)
-    /* Gtk 1.2 passes a key event to this function even if it's also
-     * defined as an accelerator.
-     * Gtk 2 doesn't do this, and this function appears not to exist there. */
-    if (fe->accelgroup &&
-        gtk_accel_group_get_entry(fe->accelgroup,
-        event->keyval, event->state))
-        return TRUE;
-#endif
-
     /* Handle mnemonics. */
     if (gtk_window_activate_key(GTK_WINDOW(fe->window), event))
         return TRUE;
@@ -1216,6 +1206,8 @@ static gint key_event(GtkWidget *widget, GdkEventKey *event, gpointer data)
 	     event->keyval == GDK_KEY_Delete ||
 	     event->keyval == GDK_KEY_KP_Delete)
         keyval = '\177';
+    else if ((event->keyval == 'z' || event->keyval == 'Z') && shift && ctrl)
+        keyval = UI_REDO;
     else if (event->string[0] && !event->string[1])
         keyval = (unsigned char)event->string[0];
     else
@@ -2348,32 +2340,34 @@ static void menu_about_event(GtkMenuItem *menuitem, gpointer data)
 #endif
 }
 
-static GtkWidget *add_menu_item_with_key(frontend *fe, GtkContainer *cont,
-                                         char *text, int key)
+static GtkWidget *add_menu_ui_item(
+    frontend *fe, GtkContainer *cont, char *text, int action,
+    int accel_key, int accel_keyqual)
 {
     GtkWidget *menuitem = gtk_menu_item_new_with_label(text);
-    int keyqual;
     gtk_container_add(cont, menuitem);
-    g_object_set_data(G_OBJECT(menuitem), "user-data", GINT_TO_POINTER(key));
+    g_object_set_data(G_OBJECT(menuitem), "user-data",
+                      GINT_TO_POINTER(action));
     g_signal_connect(G_OBJECT(menuitem), "activate",
                      G_CALLBACK(menu_key_event), fe);
-    switch (key & ~0x1F) {
-      case 0x00:
-	key += 0x60;
-	keyqual = GDK_CONTROL_MASK;
-	break;
-      case 0x40:
-	key += 0x20;
-	keyqual = GDK_SHIFT_MASK;
-	break;
-      default:
-	keyqual = 0;
-	break;
+
+    if (accel_key) {
+        /*
+         * Display a keyboard accelerator alongside this menu item.
+         * Actually this won't be processed via the usual GTK
+         * accelerator system, because we add it to a dummy
+         * accelerator group which is never actually activated on the
+         * main window; this permits back ends to override special
+         * keys like 'n' and 'r' and 'u' in some UI states. So
+         * whatever keystroke we display here will still go to
+         * key_event and be handled in the normal way.
+         */
+        gtk_widget_add_accelerator(menuitem,
+                                   "activate", fe->dummy_accelgroup,
+                                   accel_key, accel_keyqual,
+                                   GTK_ACCEL_VISIBLE | GTK_ACCEL_LOCKED);
     }
-    gtk_widget_add_accelerator(menuitem,
-			       "activate", fe->accelgroup,
-			       key, keyqual,
-			       GTK_ACCEL_VISIBLE);
+
     gtk_widget_show(menuitem);
     return menuitem;
 }
@@ -2535,8 +2529,11 @@ static frontend *new_window(char *arg, int argtype, char **error)
     gtk_container_add(GTK_CONTAINER(fe->window), GTK_WIDGET(vbox));
     gtk_widget_show(GTK_WIDGET(vbox));
 
-    fe->accelgroup = gtk_accel_group_new();
-    gtk_window_add_accel_group(GTK_WINDOW(fe->window), fe->accelgroup);
+    fe->dummy_accelgroup = gtk_accel_group_new();
+    /*
+     * Intentionally _not_ added to the window via
+     * gtk_window_add_accel_group; see menu_key_event
+     */
 
     hbox = GTK_BOX(gtk_hbox_new(FALSE, 0));
     gtk_box_pack_start(vbox, GTK_WIDGET(hbox), FALSE, FALSE, 0);
@@ -2553,7 +2550,7 @@ static frontend *new_window(char *arg, int argtype, char **error)
     menu = gtk_menu_new();
     gtk_menu_item_set_submenu(GTK_MENU_ITEM(menuitem), menu);
 
-    add_menu_item_with_key(fe, GTK_CONTAINER(menu), "New", 'n');
+    add_menu_ui_item(fe, GTK_CONTAINER(menu), "New", UI_NEWGAME, 'n', 0);
 
     menuitem = gtk_menu_item_new_with_label("Restart");
     gtk_container_add(GTK_CONTAINER(menu), menuitem);
@@ -2623,8 +2620,8 @@ static frontend *new_window(char *arg, int argtype, char **error)
     gtk_widget_show(menuitem);
 #ifndef STYLUS_BASED
     add_menu_separator(GTK_CONTAINER(menu));
-    add_menu_item_with_key(fe, GTK_CONTAINER(menu), "Undo", 'u');
-    add_menu_item_with_key(fe, GTK_CONTAINER(menu), "Redo", 'r');
+    add_menu_ui_item(fe, GTK_CONTAINER(menu), "Undo", UI_UNDO, 'u', 0);
+    add_menu_ui_item(fe, GTK_CONTAINER(menu), "Redo", UI_REDO, 'r', 0);
 #endif
     if (thegame.can_format_as_text_ever) {
 	add_menu_separator(GTK_CONTAINER(menu));
@@ -2646,7 +2643,7 @@ static frontend *new_window(char *arg, int argtype, char **error)
 	gtk_widget_show(menuitem);
     }
     add_menu_separator(GTK_CONTAINER(menu));
-    add_menu_item_with_key(fe, GTK_CONTAINER(menu), "Exit", 'q');
+    add_menu_ui_item(fe, GTK_CONTAINER(menu), "Exit", UI_QUIT, 'q', 0);
 
     menuitem = gtk_menu_item_new_with_mnemonic("_Help");
     gtk_container_add(GTK_CONTAINER(fe->menubar), menuitem);
@@ -2664,7 +2661,7 @@ static frontend *new_window(char *arg, int argtype, char **error)
 #ifdef STYLUS_BASED
     menuitem=gtk_button_new_with_mnemonic("_Redo");
     g_object_set_data(G_OBJECT(menuitem), "user-data",
-                      GINT_TO_POINTER((int)('r')));
+                      GINT_TO_POINTER(UI_REDO));
     g_signal_connect(G_OBJECT(menuitem), "clicked",
                      G_CALLBACK(menu_key_event), fe);
     gtk_box_pack_end(hbox, menuitem, FALSE, FALSE, 0);
@@ -2672,7 +2669,7 @@ static frontend *new_window(char *arg, int argtype, char **error)
 
     menuitem=gtk_button_new_with_mnemonic("_Undo");
     g_object_set_data(G_OBJECT(menuitem), "user-data",
-                      GINT_TO_POINTER((int)('u')));
+                      GINT_TO_POINTER(UI_UNDO));
     g_signal_connect(G_OBJECT(menuitem), "clicked",
                      G_CALLBACK(menu_key_event), fe);
     gtk_box_pack_end(hbox, menuitem, FALSE, FALSE, 0);
diff --git a/apps/plugins/puzzles/src/html/jspage.pl b/apps/plugins/puzzles/src/html/jspage.pl
index a21f977166..b409783f15 100755
--- a/apps/plugins/puzzles/src/html/jspage.pl
+++ b/apps/plugins/puzzles/src/html/jspage.pl
@@ -3,6 +3,17 @@
 use strict;
 use warnings;
 
+my $jspath = "";
+while ($ARGV[0] =~ /^-/) {
+    my $opt = shift @ARGV;
+    last if $opt eq "--";
+    if ($opt =~ /^--jspath=(.+)$/) {
+        $jspath = $1;
+    } else {
+        die "jspage.pl: unrecognised option '$opt'\n";
+    }
+}
+
 open my $footerfile, "<", shift @ARGV or die "footer: open: $!\n";
 my $footer = "";
 $footer .= $_ while <$footerfile>;
@@ -62,7 +73,7 @@ EOF
 <head>
 <meta http-equiv="Content-Type" content="text/html; charset=ASCII" />
 <title>${puzzlename}, ${unfinishedtitlefragment}from Simon Tatham's Portable Puzzle Collection</title>
-<script type="text/javascript" src="${filename}.js"></script>
+<script type="text/javascript" src="${jspath}${filename}.js"></script>
 <style class="text/css">
 /* Margins and centring on the top-level div for the game menu */
 #gamemenu { margin-top: 0; margin-bottom: 0.5em; text-align: center }
@@ -103,6 +114,15 @@ EOF
     color: rgba(0,0,0,0.5);
 }
 
+#gamemenu ul li.separator {
+    color: transparent;
+    border: 0;
+}
+
+#gamemenu ul li.afterseparator {
+    border-left: 1px solid rgba(0,0,0,0.3);
+}
+
 #gamemenu ul li:first-of-type {
     /* Reinstate the left border for the leftmost top-level menu item */
     border-left: 1px solid rgba(0,0,0,0.3);
@@ -196,14 +216,19 @@ ${unfinishedpara}
 
 <hr>
 <div id="puzzle" style="display: none">
-<div id="gamemenu"><ul><li id="new">New game</li
+<div id="gamemenu"><ul><li>Game...<ul
+><li id="specific">Enter game ID</li
+><li id="random">Enter random seed</li
+><li id="save">Download save file</li
+><li id="load">Upload save file</li
+></ul></li
+><li>Type...<ul id="gametype"></ul></li
+><li class="separator"></li
+><li id="new" class="afterseparator">New game</li
 ><li id="restart">Restart game</li
 ><li id="undo">Undo move</li
 ><li id="redo">Redo move</li
 ><li id="solve">Solve game</li
-><li id="specific">Enter game ID</li
-><li id="random">Enter random seed</li
-><li>Select game type<ul id="gametype" class="left"></ul></li
 ></ul></div>
 <div align=center>
   <div id="resizable" style="position:relative; left:0; top:0">
diff --git a/apps/plugins/puzzles/src/loopy.c b/apps/plugins/puzzles/src/loopy.c
index 7d3436aacb..92b27ab516 100644
--- a/apps/plugins/puzzles/src/loopy.c
+++ b/apps/plugins/puzzles/src/loopy.c
@@ -288,7 +288,7 @@ static void check_caches(const solver_state* sstate);
     {amin, omin, \
      "Width and height for this grid type must both be at least " #amin, \
      "At least one of width and height for this grid type must be at least " #omin,},
-enum { GRIDLIST(GRID_LOOPYTYPE) };
+enum { GRIDLIST(GRID_LOOPYTYPE) LOOPY_GRID_DUMMY_TERMINATOR };
 static char const *const gridnames[] = { GRIDLIST(GRID_NAME) };
 #define GRID_CONFIGS GRIDLIST(GRID_CONFIG)
 static grid_type grid_types[] = { GRIDLIST(GRID_GRIDTYPE) };
diff --git a/apps/plugins/puzzles/src/midend.c b/apps/plugins/puzzles/src/midend.c
index f80a7fa19f..09b59b25e2 100644
--- a/apps/plugins/puzzles/src/midend.c
+++ b/apps/plugins/puzzles/src/midend.c
@@ -590,33 +590,40 @@ static int midend_really_process_key(midend *me, int x, int y, int button)
     int type = MOVE, gottype = FALSE, ret = 1;
     float anim_time;
     game_state *s;
-    char *movestr;
-	
-    movestr =
-	me->ourgame->interpret_move(me->states[me->statepos-1].state,
-				    me->ui, me->drawstate, x, y, button);
+    char *movestr = NULL;
+
+    if (!IS_UI_FAKE_KEY(button)) {
+        movestr = me->ourgame->interpret_move(
+            me->states[me->statepos-1].state,
+            me->ui, me->drawstate, x, y, button);
+    }
 
     if (!movestr) {
-	if (button == 'n' || button == 'N' || button == '\x0E') {
+	if (button == 'n' || button == 'N' || button == '\x0E' ||
+            button == UI_NEWGAME) {
 	    midend_new_game(me);
 	    midend_redraw(me);
 	    goto done;		       /* never animate */
 	} else if (button == 'u' || button == 'U' ||
-		   button == '\x1A' || button == '\x1F') {
+		   button == '\x1A' || button == '\x1F' ||
+                   button == UI_UNDO) {
 	    midend_stop_anim(me);
 	    type = me->states[me->statepos-1].movetype;
 	    gottype = TRUE;
 	    if (!midend_undo(me))
 		goto done;
 	} else if (button == 'r' || button == 'R' ||
-		   button == '\x12' || button == '\x19') {
+		   button == '\x12' || button == '\x19' ||
+                   button == UI_REDO) {
 	    midend_stop_anim(me);
 	    if (!midend_redo(me))
 		goto done;
-	} else if (button == '\x13' && me->ourgame->can_solve) {
+	} else if ((button == '\x13' || button == UI_SOLVE) &&
+                   me->ourgame->can_solve) {
 	    if (midend_solve(me))
 		goto done;
-	} else if (button == 'q' || button == 'Q' || button == '\x11') {
+	} else if (button == 'q' || button == 'Q' || button == '\x11' ||
+                   button == UI_QUIT) {
 	    ret = 0;
 	    goto done;
 	} else
@@ -2059,6 +2066,8 @@ char *midend_deserialise(midend *me,
         me->ourgame->new_drawstate(me->drawing,
 				   me->states[me->statepos-1].state);
     midend_size_new_drawstate(me);
+    if (me->game_id_change_notify_function)
+        me->game_id_change_notify_function(me->game_id_change_notify_ctx);
 
     ret = NULL;                        /* success! */
 
diff --git a/apps/plugins/puzzles/src/mines.c b/apps/plugins/puzzles/src/mines.c
index 4bee0f3157..107b3ba159 100644
--- a/apps/plugins/puzzles/src/mines.c
+++ b/apps/plugins/puzzles/src/mines.c
@@ -2963,7 +2963,7 @@ static void game_redraw(drawing *dr, game_drawstate *ds,
                         float animtime, float flashtime)
 {
     int x, y;
-    int mines, markers, bg;
+    int mines, markers, closed, bg;
     int cx = -1, cy = -1, cmoved;
 
     if (flashtime) {
@@ -3013,13 +3013,15 @@ static void game_redraw(drawing *dr, game_drawstate *ds,
 
     /*
      * Now draw the tiles. Also in this loop, count up the number
-     * of mines and mine markers.
+     * of mines, mine markers, and closed squares.
      */
-    mines = markers = 0;
+    mines = markers = closed = 0;
     for (y = 0; y < ds->h; y++)
 	for (x = 0; x < ds->w; x++) {
 	    int v = state->grid[y*ds->w+x], cc = 0;
 
+            if (v < 0)
+                closed++;
 	    if (v == -1)
 		markers++;
 	    if (state->layout->mines && state->layout->mines[y*ds->w+x])
@@ -3078,7 +3080,42 @@ static void game_redraw(drawing *dr, game_drawstate *ds,
             else
                 sprintf(statusbar, "COMPLETED!");
 	} else {
+            int safe_closed = closed - mines;
 	    sprintf(statusbar, "Marked: %d / %d", markers, mines);
+            if (safe_closed > 0 && safe_closed <= 9) {
+                /*
+                 * In the situation where there's a very small number
+                 * of _non_-mine squares left unopened, it's helpful
+                 * to mention that number in the status line, to save
+                 * the player from having to count it up
+                 * painstakingly. This is particularly important if
+                 * the player has turned up the mine density to the
+                 * point where game generation resorts to its weird
+                 * pathological fallback of a very dense mine area
+                 * with a clearing in the middle, because that often
+                 * leads to a deduction you can only make by knowing
+                 * that there is (say) exactly one non-mine square to
+                 * find, and it's a real pain to have to count up two
+                 * large numbers of squares and subtract them to get
+                 * that value of 1.
+                 *
+                 * The threshold value of 8 for displaying this
+                 * information is because that's the largest number of
+                 * non-mine squares that might conceivably fit around
+                 * a single central square, and the most likely way to
+                 * _use_ this information is to observe that if all
+                 * the remaining safe squares are adjacent to _this_
+                 * square then everything else can be immediately
+                 * flagged as a mine.
+                 */
+                if (safe_closed == 1) {
+                    sprintf(statusbar + strlen(statusbar),
+                            " (1 safe square remains)");
+                } else {
+                    sprintf(statusbar + strlen(statusbar),
+                            " (%d safe squares remain)", safe_closed);
+                }
+            }
 	}
         if (ui->deaths)
             sprintf(statusbar + strlen(statusbar),
diff --git a/apps/plugins/puzzles/src/misc.c b/apps/plugins/puzzles/src/misc.c
index 2bf35d391b..816d47e43a 100644
--- a/apps/plugins/puzzles/src/misc.c
+++ b/apps/plugins/puzzles/src/misc.c
@@ -375,7 +375,7 @@ void copy_left_justified(char *buf, size_t sz, const char *str)
 /* another kludge for platforms without %g support in *printf() */
 int ftoa(char *buf, float f)
 {
-    return sprintf(buf, "%d.%06d", (int)f, (int)((f - (int)f)*1e6));
+    return sprintf(buf, "%d.%06d", (int)f, abs((int)((f - (int)f)*1e6)));
 }
 
 /* vim: set shiftwidth=4 tabstop=8: */
diff --git a/apps/plugins/puzzles/src/mkfiles.pl b/apps/plugins/puzzles/src/mkfiles.pl
index c1623dfd12..c0874ae07e 100755
--- a/apps/plugins/puzzles/src/mkfiles.pl
+++ b/apps/plugins/puzzles/src/mkfiles.pl
@@ -319,7 +319,7 @@ sub mfval($) {
     # Returns true if the argument is a known makefile type. Otherwise,
     # prints a warning and returns false;
     if (grep { $type eq $_ }
-	("vc","vcproj","cygwin","borland","lcc","gtk","am","mpw","nestedvm","osx","wce","gnustep","emcc")) {
+	("vc","vcproj","cygwin","borland","lcc","gtk","am","mpw","nestedvm","osx","wce","gnustep","emcc","clangcl")) {
 	    return 1;
 	}
     warn "$.:unknown makefile type '$type'\n";
@@ -503,6 +503,151 @@ $orig_dir = cwd;
 
 # Now we're ready to output the actual Makefiles.
 
+if (defined $makefiles{'clangcl'}) {
+    $mftyp = 'clangcl';
+    $dirpfx = &dirpfx($makefiles{'clangcl'}, "/");
+
+    ##-- Makefile for cross-compiling using clang-cl, lld-link, and
+    ##   MinGW's windres for resource compilation.
+    #
+    # This makefile allows a complete Linux-based cross-compile, but
+    # using the real Visual Studio header files and libraries. In
+    # order to run it, you will need:
+    #
+    #  - MinGW windres on your PATH.
+    #     * On Ubuntu as of 16.04, you can apt-get install
+    #       binutils-mingw-w64-x86-64 and binutils-mingw-w64-i686
+    #       which will provide (respectively) 64- and 32-bit versions,
+    #       under the names to which RCCMD is defined below.
+    #  - clang-cl and lld-link on your PATH.
+    #     * I built these from the up-to-date LLVM project trunk git
+    #       repositories, as of 2017-02-05.
+    #  - case-mashed copies of the Visual Studio include directories.
+    #     * On a real VS installation, run vcvars32.bat and look at
+    #       the resulting value of %INCLUDE%. Take a full copy of each
+    #       of those directories, and inside the copy, for each
+    #       include file that has an uppercase letter in its name,
+    #       make a lowercased symlink to it. Additionally, one of the
+    #       directories will contain files called driverspecs.h and
+    #       specstrings.h, and those will need symlinks called
+    #       DriverSpecs.h and SpecStrings.h.
+    #     * Now, on Linux, define the environment variable INCLUDE to
+    #       be a list, separated by *semicolons* (in the Windows
+    #       style), of those directories, but before all of them you
+    #       must also include lib/clang/5.0.0/include from the clang
+    #       installation area (which contains in particular a
+    #       clang-compatible stdarg.h overriding the Visual Studio
+    #       one).
+    #  - similarly case-mashed copies of the library directories.
+    #     * Again, on a real VS installation, run vcvars32 or
+    #       vcvarsx86_amd64 (as appropriate), look at %LIB%, make a
+    #       copy of each directory, and provide symlinks within that
+    #       directory so that all the files can be opened as
+    #       lowercase.
+    #     * Then set LIB to be a semicolon-separated list of those
+    #       directories (but you'll need to change which set of
+    #       directories depending on whether you want to do a 32-bit
+    #       or 64-bit build).
+    #  - for a 64-bit build, set 'Platform=x64' in the environment as
+    #    well, or else on the make command line.
+    #     * This is a variable understood only by this makefile - none
+    #       of the tools we invoke will know it - but it's consistent
+    #       with the way the VS scripts like vcvarsx86_amd64.bat set
+    #       things up, and since the environment has to change
+    #       _anyway_ between 32- and 64-bit builds (different set of
+    #       paths in $LIB) it's reasonable to have the choice of
+    #       compilation target driven by another environment variable
+    #       set in parallel with that one.
+    #  - for older versions of the VS libraries you may also have to
+    #    set EXTRA_console and/or EXTRA_windows to the name of an
+    #    object file manually extracted from one of those libraries.
+    #     * This is because old VS seems to manage its startup code by
+    #       having libcmt.lib contain lots of *crt0.obj objects, one
+    #       for each possible user entry point (main, WinMain and the
+    #       wide-char versions of both), of which the linker arranges
+    #       to include the right one by special-case code. But lld
+    #       only seems to mimic half of that code - it does include
+    #       the right crt0 object, but it doesn't also deliberately
+    #       _avoid_ including the _wrong_ ones, and since all those
+    #       objects define a common set of global symbols for other
+    #       parts of the library to use, lld may well select an
+    #       arbitrary one of them the first time it sees a reference
+    #       to one of those global symbols, and then later also select
+    #       the _right_ one for the application's entry point, causing
+    #       a multiple-definitions crash.
+    #     * So the workaround is to explicitly include the right
+    #       *crt0.obj file on the linker command line before lld even
+    #       begins searching libraries. Hence, for a console
+    #       application, you might extract crt0.obj from the library
+    #       in question and set EXTRA_console=crt0.obj, and for a GUI
+    #       application, do the same with wincrt0.obj. Then this
+    #       makefile will include the right one of those objects
+    #       alongside the matching /subsystem linker option.
+
+    open OUT, ">$makefiles{'clangcl'}"; select OUT;
+    print
+    "# Makefile for cross-compiling $project_name using clang-cl, lld-link,\n".
+    "# and MinGW's windres, using GNU make on Linux.\n".
+    "#\n# This file was created by `mkfiles.pl' from the `Recipe' file.\n".
+    "# DO NOT EDIT THIS FILE DIRECTLY; edit Recipe or mkfiles.pl instead.\n";
+    print $help;
+    print
+    "\n".
+    "CCCMD = clang-cl\n".
+    "ifeq (\$(Platform),x64)\n".
+    "CCTARGET = x86_64-pc-windows-msvc18.0.0\n".
+    "RCCMD = x86_64-w64-mingw32-windres\n".
+    "else\n".
+    "CCTARGET = i386-pc-windows-msvc18.0.0\n".
+    "RCCMD = i686-w64-mingw32-windres\n".
+    "endif\n".
+    "CC = \$(CCCMD) --target=\$(CCTARGET)\n".
+    &splitline("RC = \$(RCCMD) --preprocessor=\$(CCCMD) ".
+               "--preprocessor-arg=/TC --preprocessor-arg=/E")."\n".
+    "LD = lld-link\n".
+    "\n".
+    "# C compilation flags\n".
+    &splitline("CFLAGS = /nologo /W3 /O1 " .
+               (join " ", map {"-I$dirpfx$_"} @srcdirs) .
+               " /D_WINDOWS /D_WIN32_WINDOWS=0x401 /DWINVER=0x401 ".
+               "/D_CRT_SECURE_NO_WARNINGS")."\n".
+    "LFLAGS = /incremental:no /dynamicbase /nxcompat\n".
+    &splitline("RCFLAGS = ".(join " ", map {"-I$dirpfx$_"} @srcdirs).
+               " -DWIN32 -D_WIN32 -DWINVER=0x0400 --define MINGW32_FIX=1")."\n".
+    "\n".
+    "\n";
+    print &splitline("all:" . join "", map { " \$(BUILDDIR)$_.exe" } &progrealnames("G:C"));
+    print "\n\n";
+    foreach $p (&prognames("G:C")) {
+	($prog, $type) = split ",", $p;
+	$objstr = &objects($p, "\$(BUILDDIR)X.obj", "\$(BUILDDIR)X.res", undef);
+	print &splitline("\$(BUILDDIR)$prog.exe: " . $objstr), "\n";
+
+	$objstr = &objects($p, "\$(BUILDDIR)X.obj", "\$(BUILDDIR)X.res", "X.lib");
+	$subsys = ($type eq "G") ? "windows" : "console";
+	print &splitline("\t\$(LD) \$(LFLAGS) \$(XLFLAGS) ".
+                         "/out:\$(BUILDDIR)$prog.exe ".
+                         "/lldmap:\$(BUILDDIR)$prog.map ".
+                         "/subsystem:$subsys\$(SUBSYSVER) ".
+                         "\$(EXTRA_$subsys) $objstr")."\n\n";
+    }
+    foreach $d (&deps("\$(BUILDDIR)X.obj", "\$(BUILDDIR)X.res", $dirpfx, "/", "vc")) {
+        print &splitline(sprintf("%s: %s", $d->{obj},
+                                 join " ", @{$d->{deps}})), "\n";
+        if ($d->{obj} =~ /\.res$/) {
+            print "\t\$(RC) \$(RCFLAGS) ".$d->{deps}->[0]." -o ".$d->{obj}."\n\n";
+	} else {
+	    $deflist = join "", map { " /D$_" } @{$d->{defs}};
+            print "\t\$(CC) /Fo\$(BUILDDIR)".$d->{obj}." \$(COMPAT) \$(CFLAGS) \$(XFLAGS)$deflist /c \$<\n\n";
+        }
+    }
+    print "\nclean:\n".
+        &splitline("\trm -f \$(BUILDDIR)*.obj \$(BUILDDIR)*.exe ".
+                   "\$(BUILDDIR)*.res \$(BUILDDIR)*.map ".
+                   "\$(BUILDDIR)*.exe.manifest")."\n";
+    select STDOUT; close OUT;
+}
+
 if (defined $makefiles{'cygwin'}) {
     $mftyp = 'cygwin';
     $dirpfx = &dirpfx($makefiles{'cygwin'}, "/");
diff --git a/apps/plugins/puzzles/src/nestedvm.c b/apps/plugins/puzzles/src/nestedvm.c
index 79b797116f..f7a2ae8ec5 100644
--- a/apps/plugins/puzzles/src/nestedvm.c
+++ b/apps/plugins/puzzles/src/nestedvm.c
@@ -305,10 +305,34 @@ static int get_config(frontend *fe, int which)
     return fe->cfgret;
 }
 
-int jcallback_menu_key_event(int key)
+int jcallback_newgame_event(void)
 {
     frontend *fe = (frontend *)_fe;
-    if (!midend_process_key(fe->me, 0, 0, key))
+    if (!midend_process_key(fe->me, 0, 0, UI_NEWGAME))
+	return 42;
+    return 0;
+}
+
+int jcallback_undo_event(void)
+{
+    frontend *fe = (frontend *)_fe;
+    if (!midend_process_key(fe->me, 0, 0, UI_UNDO))
+	return 42;
+    return 0;
+}
+
+int jcallback_redo_event(void)
+{
+    frontend *fe = (frontend *)_fe;
+    if (!midend_process_key(fe->me, 0, 0, UI_REDO))
+	return 42;
+    return 0;
+}
+
+int jcallback_quit_event(void)
+{
+    frontend *fe = (frontend *)_fe;
+    if (!midend_process_key(fe->me, 0, 0, UI_QUIT))
 	return 42;
     return 0;
 }
diff --git a/apps/plugins/puzzles/src/net.c b/apps/plugins/puzzles/src/net.c
index f479f03bb7..0b3b82446d 100644
--- a/apps/plugins/puzzles/src/net.c
+++ b/apps/plugins/puzzles/src/net.c
@@ -27,13 +27,6 @@
 #define USE_DRAGGING
 #endif
 
-#define MATMUL(xr,yr,m,x,y) do { \
-    float rx, ry, xx = (x), yy = (y), *mat = (m); \
-    rx = mat[0] * xx + mat[2] * yy; \
-    ry = mat[1] * xx + mat[3] * yy; \
-    (xr) = rx; (yr) = ry; \
-} while (0)
-
 /* Direction and other bitfields */
 #define R 0x01
 #define U 0x02
@@ -65,7 +58,7 @@
 
 #define PREFERRED_TILE_SIZE 32
 #define TILE_SIZE (ds->tilesize)
-#define TILE_BORDER 1
+#define LINE_THICK ((TILE_SIZE+47)/48)
 #ifdef SMALL_SCREEN
 #define WINDOW_OFFSET 4
 #else
@@ -75,13 +68,6 @@
 #define ROTATE_TIME 0.13F
 #define FLASH_FRAME 0.07F
 
-/* Transform physical coords to game coords using game_drawstate ds */
-#define GX(x) (((x) + ds->org_x) % ds->width)
-#define GY(y) (((y) + ds->org_y) % ds->height)
-/* ...and game coords to physical coords */
-#define RX(x) (((x) + ds->width - ds->org_x) % ds->width)
-#define RY(y) (((y) + ds->height - ds->org_y) % ds->height)
-
 enum {
     COL_BACKGROUND,
     COL_LOCKED,
@@ -102,12 +88,17 @@ struct game_params {
     float barrier_probability;
 };
 
+typedef struct game_immutable_state {
+    int refcount;
+    unsigned char *barriers;
+} game_immutable_state;
+
 struct game_state {
     int width, height, wrapping, completed;
     int last_rotate_x, last_rotate_y, last_rotate_dir;
     int used_solve;
     unsigned char *tiles;
-    unsigned char *barriers;
+    struct game_immutable_state *imm;
 };
 
 #define OFFSETWH(x2,y2,x1,y1,dir,width,height) \
@@ -119,7 +110,7 @@ struct game_state {
 
 #define index(state, a, x, y) ( a[(y) * (state)->width + (x)] )
 #define tile(state, x, y)     index(state, (state)->tiles, x, y)
-#define barrier(state, x, y)  index(state, (state)->barriers, x, y)
+#define barrier(state, x, y)  index(state, (state)->imm->barriers, x, y)
 
 struct xyd {
     int x, y, direction;
@@ -462,6 +453,11 @@ static int todo_get(struct todo *todo) {
     return ret;
 }
 
+/*
+ * Return values: -1 means puzzle was proved inconsistent, 0 means we
+ * failed to narrow down to a unique solution, +1 means we solved it
+ * fully.
+ */
 static int net_solver(int w, int h, unsigned char *tiles,
 		      unsigned char *barriers, int wrapping)
 {
@@ -736,7 +732,11 @@ static int net_solver(int w, int h, unsigned char *tiles,
 #endif
 	    }
 
-	    assert(j > 0);	       /* we can't lose _all_ possibilities! */
+	    if (j == 0) {
+                /* If we've ruled out all possible orientations for a
+                 * tile, then our puzzle has no solution at all. */
+                return -1;
+            }
 
 	    if (j < i) {
 		done_something = TRUE;
@@ -816,14 +816,14 @@ static int net_solver(int w, int h, unsigned char *tiles,
     /*
      * Mark all completely determined tiles as locked.
      */
-    j = TRUE;
+    j = +1;
     for (i = 0; i < w*h; i++) {
 	if (tilestate[i * 4 + 1] == 255) {
 	    assert(tilestate[i * 4 + 0] != 255);
 	    tiles[i] = tilestate[i * 4] | LOCKED;
 	} else {
 	    tiles[i] &= ~LOCKED;
-	    j = FALSE;
+	    j = 0;
 	}
     }
 
@@ -1337,7 +1337,7 @@ static char *new_game_desc(const game_params *params, random_state *rs,
 	/*
 	 * Run the solver to check unique solubility.
 	 */
-	while (!net_solver(w, h, tiles, NULL, params->wrapping)) {
+	while (net_solver(w, h, tiles, NULL, params->wrapping) != 1) {
 	    int n = 0;
 
 	    /*
@@ -1647,12 +1647,14 @@ static game_state *new_game(midend *me, const game_params *params,
     w = state->width = params->width;
     h = state->height = params->height;
     state->wrapping = params->wrapping;
+    state->imm = snew(game_immutable_state);
+    state->imm->refcount = 1;
     state->last_rotate_dir = state->last_rotate_x = state->last_rotate_y = 0;
     state->completed = state->used_solve = FALSE;
     state->tiles = snewn(state->width * state->height, unsigned char);
     memset(state->tiles, 0, state->width * state->height);
-    state->barriers = snewn(state->width * state->height, unsigned char);
-    memset(state->barriers, 0, state->width * state->height);
+    state->imm->barriers = snewn(state->width * state->height, unsigned char);
+    memset(state->imm->barriers, 0, state->width * state->height);
 
     /*
      * Parse the game description into the grid.
@@ -1723,6 +1725,8 @@ static game_state *dup_game(const game_state *state)
     game_state *ret;
 
     ret = snew(game_state);
+    ret->imm = state->imm;
+    ret->imm->refcount++;
     ret->width = state->width;
     ret->height = state->height;
     ret->wrapping = state->wrapping;
@@ -1733,16 +1737,17 @@ static game_state *dup_game(const game_state *state)
     ret->last_rotate_y = state->last_rotate_y;
     ret->tiles = snewn(state->width * state->height, unsigned char);
     memcpy(ret->tiles, state->tiles, state->width * state->height);
-    ret->barriers = snewn(state->width * state->height, unsigned char);
-    memcpy(ret->barriers, state->barriers, state->width * state->height);
 
     return ret;
 }
 
 static void free_game(game_state *state)
 {
+    if (--state->imm->refcount == 0) {
+        sfree(state->imm->barriers);
+        sfree(state->imm);
+    }
     sfree(state->tiles);
-    sfree(state->barriers);
     sfree(state);
 }
 
@@ -1761,9 +1766,17 @@ static char *solve_game(const game_state *state, const game_state *currstate,
 	 * Run the internal solver on the provided grid. This might
 	 * not yield a complete solution.
 	 */
+        int solver_result;
+
 	memcpy(tiles, state->tiles, state->width * state->height);
-	net_solver(state->width, state->height, tiles,
-		   state->barriers, state->wrapping);
+	solver_result = net_solver(state->width, state->height, tiles,
+                                   state->imm->barriers, state->wrapping);
+
+        if (solver_result < 0) {
+            *error = "No solution exists for this puzzle";
+            sfree(tiles);
+            return NULL;
+        }
     } else {
         for (i = 0; i < state->width * state->height; i++) {
             int c = aux[i];
@@ -1990,7 +2003,7 @@ static int *compute_loops_inner(int w, int h, int wrapping,
 static int *compute_loops(const game_state *state)
 {
     return compute_loops_inner(state->width, state->height, state->wrapping,
-                               state->tiles, state->barriers);
+                               state->tiles, state->imm->barriers);
 }
 
 struct game_ui {
@@ -2051,9 +2064,8 @@ static void game_changed_state(game_ui *ui, const game_state *oldstate,
 struct game_drawstate {
     int started;
     int width, height;
-    int org_x, org_y;
     int tilesize;
-    int *visible;
+    unsigned long *visible, *to_draw;
 };
 
 /* ----------------------------------------------------------------------
@@ -2093,8 +2105,8 @@ static char *interpret_move(const game_state *state, game_ui *ui,
 	/*
 	 * The button must have been clicked on a valid tile.
 	 */
-	x -= WINDOW_OFFSET + TILE_BORDER;
-	y -= WINDOW_OFFSET + TILE_BORDER;
+	x -= WINDOW_OFFSET + LINE_THICK;
+	y -= WINDOW_OFFSET + LINE_THICK;
 	if (x < 0 || y < 0)
 	    return nullret;
 	tx = x / TILE_SIZE;
@@ -2104,8 +2116,8 @@ static char *interpret_move(const game_state *state, game_ui *ui,
         /* Transform from physical to game coords */
         tx = (tx + ui->org_x) % state->width;
         ty = (ty + ui->org_y) % state->height;
-	if (x % TILE_SIZE >= TILE_SIZE - TILE_BORDER ||
-	    y % TILE_SIZE >= TILE_SIZE - TILE_BORDER)
+	if (x % TILE_SIZE >= TILE_SIZE - LINE_THICK ||
+	    y % TILE_SIZE >= TILE_SIZE - LINE_THICK)
 	    return nullret;
 
 #ifdef USE_DRAGGING
@@ -2434,20 +2446,25 @@ static game_state *execute_move(const game_state *from, const char *move)
 static game_drawstate *game_new_drawstate(drawing *dr, const game_state *state)
 {
     game_drawstate *ds = snew(game_drawstate);
-    int i;
+    int i, ncells;
 
     ds->started = FALSE;
     ds->width = state->width;
     ds->height = state->height;
-    ds->org_x = ds->org_y = -1;
-    ds->visible = snewn(state->width * state->height, int);
+    ncells = (state->width+2) * (state->height+2);
+    ds->visible = snewn(ncells, unsigned long);
+    ds->to_draw = snewn(ncells, unsigned long);
     ds->tilesize = 0;                  /* undecided yet */
-    for (i = 0; i < state->width * state->height; i++)
+    for (i = 0; i < ncells; i++)
         ds->visible[i] = -1;
 
     return ds;
 }
 
+#define dsindex(ds, field, x, y) ((ds)->field[((y)+1)*((ds)->width+2)+((x)+1)])
+#define visible(ds, x, y) dsindex(ds, visible, x, y)
+#define todraw(ds, x, y) dsindex(ds, to_draw, x, y)
+
 static void game_free_drawstate(drawing *dr, game_drawstate *ds)
 {
     sfree(ds->visible);
@@ -2457,8 +2474,12 @@ static void game_free_drawstate(drawing *dr, game_drawstate *ds)
 static void game_compute_size(const game_params *params, int tilesize,
                               int *x, int *y)
 {
-    *x = WINDOW_OFFSET * 2 + tilesize * params->width + TILE_BORDER;
-    *y = WINDOW_OFFSET * 2 + tilesize * params->height + TILE_BORDER;
+    /* Ick: fake up `ds->tilesize' for macro expansion purposes */
+    struct { int tilesize; } ads, *ds = &ads;
+    ads.tilesize = tilesize;
+
+    *x = WINDOW_OFFSET * 2 + TILE_SIZE * params->width + LINE_THICK;
+    *y = WINDOW_OFFSET * 2 + TILE_SIZE * params->height + LINE_THICK;
 }
 
 static void game_set_size(drawing *dr, game_drawstate *ds,
@@ -2532,297 +2553,286 @@ static float *game_colours(frontend *fe, int *ncolours)
     return ret;
 }
 
-static void draw_filled_line(drawing *dr, int x1, int y1, int x2, int y2,
-			     int colour)
+static void rotated_coords(float *ox, float *oy, const float matrix[4],
+                           float cx, float cy, float ix, float iy)
 {
-    draw_line(dr, x1-1, y1, x2-1, y2, COL_WIRE);
-    draw_line(dr, x1+1, y1, x2+1, y2, COL_WIRE);
-    draw_line(dr, x1, y1-1, x2, y2-1, COL_WIRE);
-    draw_line(dr, x1, y1+1, x2, y2+1, COL_WIRE);
-    draw_line(dr, x1, y1, x2, y2, colour);
+    *ox = matrix[0] * ix + matrix[2] * iy + cx;
+    *oy = matrix[1] * ix + matrix[3] * iy + cy;
 }
 
-static void draw_rect_coords(drawing *dr, int x1, int y1, int x2, int y2,
-                             int colour)
+/* Flags describing the visible features of a tile. */
+#define TILE_BARRIER_SHIFT            0  /* 4 bits: R U L D */
+#define TILE_BARRIER_CORNER_SHIFT     4  /* 4 bits: RU UL LD DR */
+#define TILE_KEYBOARD_CURSOR      (1<<8) /* 1 bit if cursor is here */
+#define TILE_WIRE_SHIFT               9  /* 8 bits: RR UU LL DD
+                                          * Each pair: 0=no wire, 1=unpowered,
+                                          * 2=powered, 3=loop err highlight */
+#define TILE_ENDPOINT_SHIFT          17  /* 2 bits: 0=no endpoint, 1=unpowered,
+                                          * 2=powered, 3=power-source square */
+#define TILE_WIRE_ON_EDGE_SHIFT      19  /* 8 bits: RR UU LL DD,
+                                          * same encoding as TILE_WIRE_SHIFT */
+#define TILE_ROTATING          (1UL<<27) /* 1 bit if tile is rotating */
+#define TILE_LOCKED            (1UL<<28) /* 1 bit if tile is locked */
+
+static void draw_wires(drawing *dr, int cx, int cy, int radius,
+                       unsigned long tile, int bitmap,
+                       int colour, int halfwidth, const float matrix[4])
 {
-    int mx = (x1 < x2 ? x1 : x2);
-    int my = (y1 < y2 ? y1 : y2);
-    int dx = (x2 + x1 - 2*mx + 1);
-    int dy = (y2 + y1 - 2*my + 1);
+    float fpoints[12*2];
+    int points[12*2];
+    int npoints, d, dsh, i;
+    int any_wire_this_colour = FALSE;
+    float xf, yf;
 
-    draw_rect(dr, mx, my, dx, dy, colour);
-}
+    npoints = 0;
+    for (d = 1, dsh = 0; d < 16; d *= 2, dsh++) {
+        int wiretype = (tile >> (TILE_WIRE_SHIFT + 2*dsh)) & 3;
 
-/*
- * draw_barrier_corner() and draw_barrier() are passed physical coords
- */
-static void draw_barrier_corner(drawing *dr, game_drawstate *ds,
-                                int x, int y, int dx, int dy, int phase)
-{
-    int bx = WINDOW_OFFSET + TILE_SIZE * x;
-    int by = WINDOW_OFFSET + TILE_SIZE * y;
-    int x1, y1;
+        fpoints[2*npoints+0] = halfwidth * (X(d) + X(C(d)));
+        fpoints[2*npoints+1] = halfwidth * (Y(d) + Y(C(d)));
+        npoints++;
 
-    x1 = (dx > 0 ? TILE_SIZE+TILE_BORDER-1 : 0);
-    y1 = (dy > 0 ? TILE_SIZE+TILE_BORDER-1 : 0);
+        if (bitmap & (1 << wiretype)) {
+            fpoints[2*npoints+0] = radius * X(d) + halfwidth * X(C(d));
+            fpoints[2*npoints+1] = radius * Y(d) + halfwidth * Y(C(d));
+            npoints++;
+            fpoints[2*npoints+0] = radius * X(d) + halfwidth * X(A(d));
+            fpoints[2*npoints+1] = radius * Y(d) + halfwidth * Y(A(d));
+            npoints++;
 
-    if (phase == 0) {
-        draw_rect_coords(dr, bx+x1+dx, by+y1,
-                         bx+x1-TILE_BORDER*dx, by+y1-(TILE_BORDER-1)*dy,
-                         COL_WIRE);
-        draw_rect_coords(dr, bx+x1, by+y1+dy,
-                         bx+x1-(TILE_BORDER-1)*dx, by+y1-TILE_BORDER*dy,
-                         COL_WIRE);
-    } else {
-        draw_rect_coords(dr, bx+x1, by+y1,
-                         bx+x1-(TILE_BORDER-1)*dx, by+y1-(TILE_BORDER-1)*dy,
-                         COL_BARRIER);
+            any_wire_this_colour = TRUE;
+        }
     }
-}
 
-static void draw_barrier(drawing *dr, game_drawstate *ds,
-                         int x, int y, int dir, int phase)
-{
-    int bx = WINDOW_OFFSET + TILE_SIZE * x;
-    int by = WINDOW_OFFSET + TILE_SIZE * y;
-    int x1, y1, w, h;
+    if (!any_wire_this_colour)
+        return;
 
-    x1 = (X(dir) > 0 ? TILE_SIZE : X(dir) == 0 ? TILE_BORDER : 0);
-    y1 = (Y(dir) > 0 ? TILE_SIZE : Y(dir) == 0 ? TILE_BORDER : 0);
-    w = (X(dir) ? TILE_BORDER : TILE_SIZE - TILE_BORDER);
-    h = (Y(dir) ? TILE_BORDER : TILE_SIZE - TILE_BORDER);
-
-    if (phase == 0) {
-        draw_rect(dr, bx+x1-X(dir), by+y1-Y(dir), w, h, COL_WIRE);
-    } else {
-        draw_rect(dr, bx+x1, by+y1, w, h, COL_BARRIER);
+    for (i = 0; i < npoints; i++) {
+        rotated_coords(&xf, &yf, matrix, cx, cy, fpoints[2*i], fpoints[2*i+1]);
+        points[2*i] = 0.5 + xf;
+        points[2*i+1] = 0.5 + yf;
     }
+
+    draw_polygon(dr, points, npoints, colour, colour);
 }
 
-/*
- * draw_tile() is passed physical coordinates
- */
-static void draw_tile(drawing *dr, const game_state *state, game_drawstate *ds,
-                      int x, int y, int tile, int src, float angle, int cursor)
+static void draw_tile(drawing *dr, game_drawstate *ds, int x, int y,
+                      unsigned long tile, float angle)
 {
-    int bx = WINDOW_OFFSET + TILE_SIZE * x;
-    int by = WINDOW_OFFSET + TILE_SIZE * y;
+    int tx, ty;
+    int clipx, clipy, clipX, clipY, clipw, cliph;
+    int border_br = LINE_THICK/2, border_tl = LINE_THICK - border_br;
+    int barrier_outline_thick = (LINE_THICK+1)/2;
+    int bg, d, dsh, pass;
+    int cx, cy, radius;
     float matrix[4];
-    float cx, cy, ex, ey, tx, ty;
-    int dir, col, phase;
+
+    tx = WINDOW_OFFSET + TILE_SIZE * x + border_br;
+    ty = WINDOW_OFFSET + TILE_SIZE * y + border_br;
 
     /*
-     * When we draw a single tile, we must draw everything up to
-     * and including the borders around the tile. This means that
-     * if the neighbouring tiles have connections to those borders,
-     * we must draw those connections on the borders themselves.
+     * Clip to the tile boundary, with adjustments if we're drawing
+     * just outside the grid.
      */
-
-    clip(dr, bx, by, TILE_SIZE+TILE_BORDER, TILE_SIZE+TILE_BORDER);
+    clipx = tx; clipX = tx + TILE_SIZE;
+    clipy = ty; clipY = ty + TILE_SIZE;
+    if (x == -1) {
+        clipx = clipX - border_br - barrier_outline_thick;
+    } else if (x == ds->width) {
+        clipX = clipx + border_tl + barrier_outline_thick;
+    }
+    if (y == -1) {
+        clipy = clipY - border_br - barrier_outline_thick;
+    } else if (y == ds->height) {
+        clipY = clipy + border_tl + barrier_outline_thick;
+    }
+    clipw = clipX - clipx;
+    cliph = clipY - clipy;
+    clip(dr, clipx, clipy, clipw, cliph);
 
     /*
-     * So. First blank the tile out completely: draw a big
-     * rectangle in border colour, and a smaller rectangle in
-     * background colour to fill it in.
+     * Clear the clip region.
      */
-    draw_rect(dr, bx, by, TILE_SIZE+TILE_BORDER, TILE_SIZE+TILE_BORDER,
-              COL_BORDER);
-    draw_rect(dr, bx+TILE_BORDER, by+TILE_BORDER,
-              TILE_SIZE-TILE_BORDER, TILE_SIZE-TILE_BORDER,
-              tile & LOCKED ? COL_LOCKED : COL_BACKGROUND);
+    bg = (tile & TILE_LOCKED) ? COL_LOCKED : COL_BACKGROUND;
+    draw_rect(dr, clipx, clipy, clipw, cliph, bg);
 
     /*
-     * Draw an inset outline rectangle as a cursor, in whichever of
-     * COL_LOCKED and COL_BACKGROUND we aren't currently drawing
-     * in.
+     * Draw the grid lines.
      */
-    if (cursor) {
-	draw_line(dr, bx+TILE_SIZE/8, by+TILE_SIZE/8,
-		  bx+TILE_SIZE/8, by+TILE_SIZE-TILE_SIZE/8,
-		  tile & LOCKED ? COL_BACKGROUND : COL_LOCKED);
-	draw_line(dr, bx+TILE_SIZE/8, by+TILE_SIZE/8,
-		  bx+TILE_SIZE-TILE_SIZE/8, by+TILE_SIZE/8,
-		  tile & LOCKED ? COL_BACKGROUND : COL_LOCKED);
-	draw_line(dr, bx+TILE_SIZE-TILE_SIZE/8, by+TILE_SIZE/8,
-		  bx+TILE_SIZE-TILE_SIZE/8, by+TILE_SIZE-TILE_SIZE/8,
-		  tile & LOCKED ? COL_BACKGROUND : COL_LOCKED);
-	draw_line(dr, bx+TILE_SIZE/8, by+TILE_SIZE-TILE_SIZE/8,
-		  bx+TILE_SIZE-TILE_SIZE/8, by+TILE_SIZE-TILE_SIZE/8,
-		  tile & LOCKED ? COL_BACKGROUND : COL_LOCKED);
+    {
+        int gridl = (x == -1 ? tx+TILE_SIZE-border_br : tx);
+        int gridr = (x == ds->width ? tx+border_tl : tx+TILE_SIZE);
+        int gridu = (y == -1 ? ty+TILE_SIZE-border_br : ty);
+        int gridd = (y == ds->height ? ty+border_tl : ty+TILE_SIZE);
+        if (x >= 0)
+            draw_rect(dr, tx, gridu, border_tl, gridd-gridu, COL_BORDER);
+        if (y >= 0)
+            draw_rect(dr, gridl, ty, gridr-gridl, border_tl, COL_BORDER);
+        if (x < ds->width)
+            draw_rect(dr, tx+TILE_SIZE-border_br, gridu,
+                      border_br, gridd-gridu, COL_BORDER);
+        if (y < ds->height)
+            draw_rect(dr, gridl, ty+TILE_SIZE-border_br,
+                      gridr-gridl, border_br, COL_BORDER);
     }
 
     /*
-     * Set up the rotation matrix.
+     * Draw the keyboard cursor.
      */
-    matrix[0] = (float)cos(angle * PI / 180.0);
-    matrix[1] = (float)-sin(angle * PI / 180.0);
-    matrix[2] = (float)sin(angle * PI / 180.0);
-    matrix[3] = (float)cos(angle * PI / 180.0);
+    if (tile & TILE_KEYBOARD_CURSOR) {
+        int cursorcol = (tile & TILE_LOCKED) ? COL_BACKGROUND : COL_LOCKED;
+        int inset_outer = TILE_SIZE/8, inset_inner = inset_outer + LINE_THICK;
+        draw_rect(dr, tx + inset_outer, ty + inset_outer,
+                  TILE_SIZE - 2*inset_outer, TILE_SIZE - 2*inset_outer,
+                  cursorcol);
+        draw_rect(dr, tx + inset_inner, ty + inset_inner,
+                  TILE_SIZE - 2*inset_inner, TILE_SIZE - 2*inset_inner,
+                  bg);
+    }
+
+    radius = (TILE_SIZE+1)/2;
+    cx = tx + radius;
+    cy = ty + radius;
+    radius++;
+
+    /*
+     * Draw protrusions into this cell's edges of wires in
+     * neighbouring cells, as given by the TILE_WIRE_ON_EDGE_SHIFT
+     * flags. We only draw each of these if there _isn't_ a wire of
+     * our own that's going to overlap it, which means either the
+     * corresponding TILE_WIRE_SHIFT flag is zero, or else the
+     * TILE_ROTATING flag is set (so that our main wire won't be drawn
+     * in quite that place anyway).
+     */
+    for (d = 1, dsh = 0; d < 16; d *= 2, dsh++) {
+        int edgetype = ((tile >> (TILE_WIRE_ON_EDGE_SHIFT + 2*dsh)) & 3);
+        if (edgetype == 0)
+            continue;             /* there isn't a wire on the edge */
+        if (!(tile & TILE_ROTATING) &&
+            ((tile >> (TILE_WIRE_SHIFT + 2*dsh)) & 3) != 0)
+            continue;     /* wire on edge would be overdrawn anyway */
+
+        for (pass = 0; pass < 2; pass++) {
+            int x, y, w, h;
+            int col = (pass == 0 || edgetype == 1 ? COL_WIRE :
+                       edgetype == 2 ? COL_POWERED : COL_LOOP);
+            int halfwidth = pass == 0 ? 2*LINE_THICK-1 : LINE_THICK-1;
+
+            if (X(d) < 0) {
+                x = tx;
+                w = border_tl;
+            } else if (X(d) > 0) {
+                x = tx + TILE_SIZE - border_br;
+                w = border_br;
+            } else {
+                x = cx - halfwidth;
+                w = 2 * halfwidth + 1;
+            }
+
+            if (Y(d) < 0) {
+                y = ty;
+                h = border_tl;
+            } else if (Y(d) > 0) {
+                y = ty + TILE_SIZE - border_br;
+                h = border_br;
+            } else {
+                y = cy - halfwidth;
+                h = 2 * halfwidth + 1;
+            }
+
+            draw_rect(dr, x, y, w, h, col);
+        }
+    }
+
+    /*
+     * Set up the rotation matrix for the main cell contents, i.e.
+     * everything that is centred in the grid square and optionally
+     * rotated by an arbitrary angle about that centre point.
+     */
+    if (tile & TILE_ROTATING) {
+        matrix[0] = (float)cos(angle * PI / 180.0);
+        matrix[2] = (float)sin(angle * PI / 180.0);
+    } else {
+        matrix[0] = 1.0F;
+        matrix[2] = 0.0F;
+    }
+    matrix[3] = matrix[0];
+    matrix[1] = -matrix[2];
 
     /*
      * Draw the wires.
      */
-    cx = cy = TILE_BORDER + (TILE_SIZE-TILE_BORDER) / 2.0F - 0.5F;
-    col = (tile & ACTIVE ? COL_POWERED : COL_WIRE);
-    for (dir = 1; dir < 0x10; dir <<= 1) {
-        if (tile & dir) {
-            ex = (TILE_SIZE - TILE_BORDER - 1.0F) / 2.0F * X(dir);
-            ey = (TILE_SIZE - TILE_BORDER - 1.0F) / 2.0F * Y(dir);
-            MATMUL(tx, ty, matrix, ex, ey);
-            draw_filled_line(dr, bx+(int)cx, by+(int)cy,
-			     bx+(int)(cx+tx), by+(int)(cy+ty),
-			     COL_WIRE);
-        }
-    }
-    for (dir = 1; dir < 0x10; dir <<= 1) {
-        if (tile & dir) {
-            ex = (TILE_SIZE - TILE_BORDER - 1.0F) / 2.0F * X(dir);
-            ey = (TILE_SIZE - TILE_BORDER - 1.0F) / 2.0F * Y(dir);
-            MATMUL(tx, ty, matrix, ex, ey);
-            draw_line(dr, bx+(int)cx, by+(int)cy,
-		      bx+(int)(cx+tx), by+(int)(cy+ty),
-                      (tile & LOOP(dir)) ? COL_LOOP : col);
-        }
-    }
-    /* If we've drawn any loop-highlighted arms, make sure the centre
-     * point is loop-coloured rather than a later arm overwriting it. */
-    if (tile & (RLOOP | ULOOP | LLOOP | DLOOP))
-        draw_rect(dr, bx+(int)cx, by+(int)cy, 1, 1, COL_LOOP);
+    draw_wires(dr, cx, cy, radius, tile,
+               0xE, COL_WIRE, 2*LINE_THICK-1, matrix);
+    draw_wires(dr, cx, cy, radius, tile,
+               0x4, COL_POWERED, LINE_THICK-1, matrix);
+    draw_wires(dr, cx, cy, radius, tile,
+               0x8, COL_LOOP, LINE_THICK-1, matrix);
 
     /*
-     * Draw the box in the middle. We do this in blue if the tile
-     * is an unpowered endpoint, in cyan if the tile is a powered
-     * endpoint, in black if the tile is the centrepiece, and
-     * otherwise not at all.
+     * Draw the central box.
      */
-    col = -1;
-    if (src)
-        col = COL_WIRE;
-    else if (COUNT(tile) == 1) {
-        col = (tile & ACTIVE ? COL_POWERED : COL_ENDPOINT);
-    }
-    if (col >= 0) {
-        int i, points[8];
+    for (pass = 0; pass < 2; pass++) {
+        int endtype = (tile >> TILE_ENDPOINT_SHIFT) & 3;
+        if (endtype) {
+            int i, points[8], col;
+            float boxr = TILE_SIZE * 0.24F + (pass == 0 ? LINE_THICK-1 : 0);
 
-        points[0] = +1; points[1] = +1;
-        points[2] = +1; points[3] = -1;
-        points[4] = -1; points[5] = -1;
-        points[6] = -1; points[7] = +1;
+            col = (pass == 0 || endtype == 3 ? COL_WIRE :
+                   endtype == 2 ? COL_POWERED : COL_ENDPOINT);
 
-        for (i = 0; i < 8; i += 2) {
-            ex = (TILE_SIZE * 0.24F) * points[i];
-            ey = (TILE_SIZE * 0.24F) * points[i+1];
-            MATMUL(tx, ty, matrix, ex, ey);
-            points[i] = bx+(int)(cx+tx);
-            points[i+1] = by+(int)(cy+ty);
-        }
+            points[0] = +1; points[1] = +1;
+            points[2] = +1; points[3] = -1;
+            points[4] = -1; points[5] = -1;
+            points[6] = -1; points[7] = +1;
 
-        draw_polygon(dr, points, 4, col, COL_WIRE);
-    }
-
-    /*
-     * Draw the points on the border if other tiles are connected
-     * to us.
-     */
-    for (dir = 1; dir < 0x10; dir <<= 1) {
-        int dx, dy, px, py, lx, ly, vx, vy, ox, oy;
-
-        dx = X(dir);
-        dy = Y(dir);
-
-        ox = x + dx;
-        oy = y + dy;
-
-        if (ox < 0 || ox >= state->width || oy < 0 || oy >= state->height)
-            continue;
-
-        if (!(tile(state, GX(ox), GY(oy)) & F(dir)))
-            continue;
-
-        px = bx + (int)(dx>0 ? TILE_SIZE + TILE_BORDER - 1 : dx<0 ? 0 : cx);
-        py = by + (int)(dy>0 ? TILE_SIZE + TILE_BORDER - 1 : dy<0 ? 0 : cy);
-        lx = dx * (TILE_BORDER-1);
-        ly = dy * (TILE_BORDER-1);
-        vx = (dy ? 1 : 0);
-        vy = (dx ? 1 : 0);
-
-        if (angle == 0.0 && (tile & dir)) {
-            /*
-             * If we are fully connected to the other tile, we must
-             * draw right across the tile border. (We can use our
-             * own ACTIVE state to determine what colour to do this
-             * in: if we are fully connected to the other tile then
-             * the two ACTIVE states will be the same.)
-             */
-            draw_rect_coords(dr, px-vx, py-vy, px+lx+vx, py+ly+vy, COL_WIRE);
-            draw_rect_coords(dr, px, py, px+lx, py+ly,
-                             ((tile & LOOP(dir)) ? COL_LOOP :
-                              (tile & ACTIVE) ? COL_POWERED :
-                              COL_WIRE));
-        } else {
-            /*
-             * The other tile extends into our border, but isn't
-             * actually connected to us. Just draw a single black
-             * dot.
-             */
-            draw_rect_coords(dr, px, py, px, py, COL_WIRE);
-        }
-    }
-
-    /*
-     * Draw barrier corners, and then barriers.
-     */
-    for (phase = 0; phase < 2; phase++) {
-        for (dir = 1; dir < 0x10; dir <<= 1) {
-            int x1, y1, corner = FALSE;
-            /*
-             * If at least one barrier terminates at the corner
-             * between dir and A(dir), draw a barrier corner.
-             */
-            if (barrier(state, GX(x), GY(y)) & (dir | A(dir))) {
-                corner = TRUE;
-            } else {
-                /*
-                 * Only count barriers terminating at this corner
-                 * if they're physically next to the corner. (That
-                 * is, if they've wrapped round from the far side
-                 * of the screen, they don't count.)
-                 */
-                x1 = x + X(dir);
-                y1 = y + Y(dir);
-                if (x1 >= 0 && x1 < state->width &&
-                    y1 >= 0 && y1 < state->height &&
-                    (barrier(state, GX(x1), GY(y1)) & A(dir))) {
-                    corner = TRUE;
-                } else {
-                    x1 = x + X(A(dir));
-                    y1 = y + Y(A(dir));
-                    if (x1 >= 0 && x1 < state->width &&
-                        y1 >= 0 && y1 < state->height &&
-                        (barrier(state, GX(x1), GY(y1)) & dir))
-                        corner = TRUE;
-                }
+            for (i = 0; i < 8; i += 2) {
+                float x, y;
+                rotated_coords(&x, &y, matrix, cx, cy,
+                               boxr * points[i], boxr * points[i+1]);
+                points[i] = x + 0.5;
+                points[i+1] = y + 0.5;
             }
 
-            if (corner) {
-                /*
-                 * At least one barrier terminates here. Draw a
-                 * corner.
-                 */
-                draw_barrier_corner(dr, ds, x, y,
-                                    X(dir)+X(A(dir)), Y(dir)+Y(A(dir)),
-                                    phase);
-            }
+            draw_polygon(dr, points, 4, col, COL_WIRE);
         }
-
-        for (dir = 1; dir < 0x10; dir <<= 1)
-            if (barrier(state, GX(x), GY(y)) & dir)
-                draw_barrier(dr, ds, x, y, dir, phase);
     }
 
+    /*
+     * Draw barriers along grid edges.
+     */
+    for (pass = 0; pass < 2; pass++) {
+        int btl = border_tl, bbr = border_br, col = COL_BARRIER;
+        if (pass == 0) {
+            btl += barrier_outline_thick;
+            bbr += barrier_outline_thick;
+            col = COL_WIRE;
+        }
+
+        if (tile & (L << TILE_BARRIER_SHIFT))
+            draw_rect(dr, tx, ty, btl, TILE_SIZE, col);
+        if (tile & (R << TILE_BARRIER_SHIFT))
+            draw_rect(dr, tx+TILE_SIZE-bbr, ty, bbr, TILE_SIZE, col);
+        if (tile & (U << TILE_BARRIER_SHIFT))
+            draw_rect(dr, tx, ty, TILE_SIZE, btl, col);
+        if (tile & (D << TILE_BARRIER_SHIFT))
+            draw_rect(dr, tx, ty+TILE_SIZE-bbr, TILE_SIZE, bbr, col);
+
+        if (tile & (R << TILE_BARRIER_CORNER_SHIFT))
+            draw_rect(dr, tx+TILE_SIZE-bbr, ty, bbr, btl, col);
+        if (tile & (U << TILE_BARRIER_CORNER_SHIFT))
+            draw_rect(dr, tx, ty, btl, btl, col);
+        if (tile & (L << TILE_BARRIER_CORNER_SHIFT))
+            draw_rect(dr, tx, ty+TILE_SIZE-bbr, btl, bbr, col);
+        if (tile & (D << TILE_BARRIER_CORNER_SHIFT))
+            draw_rect(dr, tx+TILE_SIZE-bbr, ty+TILE_SIZE-bbr, bbr, bbr, col);
+    }
+
+    /*
+     * Unclip and draw update, to finish.
+     */
     unclip(dr);
-
-    draw_update(dr, bx, by, TILE_SIZE+TILE_BORDER, TILE_SIZE+TILE_BORDER);
+    draw_update(dr, clipx, clipy, clipw, cliph);
 }
 
 static void game_redraw(drawing *dr, game_drawstate *ds,
@@ -2830,73 +2840,26 @@ static void game_redraw(drawing *dr, game_drawstate *ds,
                         int dir, const game_ui *ui,
                         float t, float ft)
 {
-    int x, y, tx, ty, frame, last_rotate_dir, moved_origin = FALSE;
+    int tx, ty, dx, dy, d, dsh, last_rotate_dir, frame;
     unsigned char *active;
     int *loops;
     float angle = 0.0;
 
     /*
-     * Clear the screen, and draw the exterior barrier lines, if
-     * this is our first call or if the origin has changed.
+     * Clear the screen on our first call.
      */
-    if (!ds->started || ui->org_x != ds->org_x || ui->org_y != ds->org_y) {
-        int phase;
+    if (!ds->started) {
+        int w, h;
+        game_params params;
 
         ds->started = TRUE;
 
-        draw_rect(dr, 0, 0, 
-                  WINDOW_OFFSET * 2 + TILE_SIZE * state->width + TILE_BORDER,
-                  WINDOW_OFFSET * 2 + TILE_SIZE * state->height + TILE_BORDER,
-                  COL_BACKGROUND);
+        params.width = ds->width;
+        params.height = ds->height;
+        game_compute_size(&params, TILE_SIZE, &w, &h);
 
-        ds->org_x = ui->org_x;
-        ds->org_y = ui->org_y;
-        moved_origin = TRUE;
-
-        draw_update(dr, 0, 0, 
-                    WINDOW_OFFSET*2 + TILE_SIZE*state->width + TILE_BORDER,
-                    WINDOW_OFFSET*2 + TILE_SIZE*state->height + TILE_BORDER);
-
-        for (phase = 0; phase < 2; phase++) {
-
-            for (x = 0; x < ds->width; x++) {
-                if (x+1 < ds->width) {
-                    if (barrier(state, GX(x), GY(0)) & R)
-                        draw_barrier_corner(dr, ds, x, -1, +1, +1, phase);
-                    if (barrier(state, GX(x), GY(ds->height-1)) & R)
-                        draw_barrier_corner(dr, ds, x, ds->height, +1, -1, phase);
-                }
-                if (barrier(state, GX(x), GY(0)) & U) {
-                    draw_barrier_corner(dr, ds, x, -1, -1, +1, phase);
-                    draw_barrier_corner(dr, ds, x, -1, +1, +1, phase);
-                    draw_barrier(dr, ds, x, -1, D, phase);
-                }
-                if (barrier(state, GX(x), GY(ds->height-1)) & D) {
-                    draw_barrier_corner(dr, ds, x, ds->height, -1, -1, phase);
-                    draw_barrier_corner(dr, ds, x, ds->height, +1, -1, phase);
-                    draw_barrier(dr, ds, x, ds->height, U, phase);
-                }
-            }
-
-            for (y = 0; y < ds->height; y++) {
-                if (y+1 < ds->height) {
-                    if (barrier(state, GX(0), GY(y)) & D)
-                        draw_barrier_corner(dr, ds, -1, y, +1, +1, phase);
-                    if (barrier(state, GX(ds->width-1), GY(y)) & D)
-                        draw_barrier_corner(dr, ds, ds->width, y, -1, +1, phase);
-                }
-                if (barrier(state, GX(0), GY(y)) & L) {
-                    draw_barrier_corner(dr, ds, -1, y, +1, -1, phase);
-                    draw_barrier_corner(dr, ds, -1, y, +1, +1, phase);
-                    draw_barrier(dr, ds, -1, y, R, phase);
-                }
-                if (barrier(state, GX(ds->width-1), GY(y)) & R) {
-                    draw_barrier_corner(dr, ds, ds->width, y, -1, -1, phase);
-                    draw_barrier_corner(dr, ds, ds->width, y, -1, +1, phase);
-                    draw_barrier(dr, ds, ds->width, y, L, phase);
-                }
-            }
-        }
+        draw_rect(dr, 0, 0, w, h, COL_BACKGROUND);
+        draw_update(dr, 0, 0, w, h);
     }
 
     tx = ty = -1;
@@ -2913,30 +2876,83 @@ static void game_redraw(drawing *dr, game_drawstate *ds,
         state = oldstate;
     }
 
-    frame = -1;
     if (ft > 0) {
         /*
          * We're animating a completion flash. Find which frame
          * we're at.
          */
         frame = (int)(ft / FLASH_FRAME);
+    } else {
+        frame = 0;
     }
 
     /*
-     * Draw any tile which differs from the way it was last drawn.
+     * Build up a map of what we want every tile to look like. We
+     * include tiles one square outside the grid, for the outer edges
+     * of barriers.
      */
     active = compute_active(state, ui->cx, ui->cy);
     loops = compute_loops(state);
 
-    for (x = 0; x < ds->width; x++)
-        for (y = 0; y < ds->height; y++) {
-            int c = tile(state, GX(x), GY(y)) |
-                index(state, active, GX(x), GY(y)) |
-                index(state, loops, GX(x), GY(y));
-            int is_src = GX(x) == ui->cx && GY(y) == ui->cy;
-            int is_anim = GX(x) == tx && GY(y) == ty;
-            int is_cursor = ui->cur_visible &&
-                            GX(x) == ui->cur_x && GY(y) == ui->cur_y;
+    for (dy = -1; dy < ds->height+1; dy++) {
+        for (dx = -1; dx < ds->width+1; dx++) {
+            todraw(ds, dx, dy) = 0;
+        }
+    }
+
+    for (dy = 0; dy < ds->height; dy++) {
+        int gy = (dy + ui->org_y) % ds->height;
+        for (dx = 0; dx < ds->width; dx++) {
+            int gx = (dx + ui->org_x) % ds->width;
+            int t = (tile(state, gx, gy) |
+                     index(state, loops, gx, gy) |
+                     index(state, active, gx, gy));
+
+            for (d = 1, dsh = 0; d < 16; d *= 2, dsh++) {
+                if (barrier(state, gx, gy) & d) {
+                    todraw(ds, dx, dy) |=
+                        d << TILE_BARRIER_SHIFT;
+                    todraw(ds, dx + X(d), dy + Y(d)) |=
+                        F(d) << TILE_BARRIER_SHIFT;
+                    todraw(ds, dx + X(A(d)), dy + Y(A(d))) |=
+                        C(d) << TILE_BARRIER_CORNER_SHIFT;
+                    todraw(ds, dx + X(A(d)) + X(d), dy + Y(A(d)) + Y(d)) |=
+                        F(d) << TILE_BARRIER_CORNER_SHIFT;
+                    todraw(ds, dx + X(C(d)), dy + Y(C(d))) |=
+                        d << TILE_BARRIER_CORNER_SHIFT;
+                    todraw(ds, dx + X(C(d)) + X(d), dy + Y(C(d)) + Y(d)) |=
+                        A(d) << TILE_BARRIER_CORNER_SHIFT;
+                }
+
+                if (t & d) {
+                    int edgeval = (t & LOOP(d) ? 3 : t & ACTIVE ? 2 : 1);
+                    todraw(ds, dx, dy) |= edgeval << (TILE_WIRE_SHIFT + dsh*2);
+                    if (!(gx == tx && gy == ty)) {
+                        todraw(ds, dx + X(d), dy + Y(d)) |=
+                            edgeval << (TILE_WIRE_ON_EDGE_SHIFT + (dsh ^ 2)*2);
+                    }
+                }
+            }
+
+            if (ui->cur_visible && gx == ui->cur_x && gy == ui->cur_y)
+                todraw(ds, dx, dy) |= TILE_KEYBOARD_CURSOR;
+
+            if (gx == tx && gy == ty)
+                todraw(ds, dx, dy) |= TILE_ROTATING;
+
+            if (gx == ui->cx && gy == ui->cy) {
+                todraw(ds, dx, dy) |= 3 << TILE_ENDPOINT_SHIFT;
+            } else if ((t & 0xF) != R && (t & 0xF) != U && 
+                       (t & 0xF) != L && (t & 0xF) != D) {
+                /* this is not an endpoint tile */
+            } else if (t & ACTIVE) {
+                todraw(ds, dx, dy) |= 2 << TILE_ENDPOINT_SHIFT;
+            } else {
+                todraw(ds, dx, dy) |= 1 << TILE_ENDPOINT_SHIFT;
+            }
+
+            if (t & LOCKED)
+                todraw(ds, dx, dy) |= TILE_LOCKED;
 
             /*
              * In a completion flash, we adjust the LOCKED bit
@@ -2944,31 +2960,36 @@ static void game_redraw(drawing *dr, game_drawstate *ds,
              * the frame number.
              */
             if (frame >= 0) {
-                int rcx = RX(ui->cx), rcy = RY(ui->cy);
+                int rcx = (ui->cx + ds->width - ui->org_x) % ds->width;
+                int rcy = (ui->cy + ds->height - ui->org_y) % ds->height;
                 int xdist, ydist, dist;
-                xdist = (x < rcx ? rcx - x : x - rcx);
-                ydist = (y < rcy ? rcy - y : y - rcy);
+                xdist = (dx < rcx ? rcx - dx : dx - rcx);
+                ydist = (dy < rcy ? rcy - dy : dy - rcy);
                 dist = (xdist > ydist ? xdist : ydist);
 
-                if (frame >= dist && frame < dist+4) {
-                    int lock = (frame - dist) & 1;
-                    lock = lock ? LOCKED : 0;
-                    c = (c &~ LOCKED) | lock;
-                }
-            }
-
-            if (moved_origin ||
-                index(state, ds->visible, x, y) != c ||
-                index(state, ds->visible, x, y) == -1 ||
-                is_src || is_anim || is_cursor) {
-                draw_tile(dr, state, ds, x, y, c,
-                          is_src, (is_anim ? angle : 0.0F), is_cursor);
-                if (is_src || is_anim || is_cursor)
-                    index(state, ds->visible, x, y) = -1;
-                else
-                    index(state, ds->visible, x, y) = c;
+                if (frame >= dist && frame < dist+4 &&
+                    ((frame - dist) & 1))
+                    todraw(ds, dx, dy) ^= TILE_LOCKED;
             }
         }
+    }
+
+    /*
+     * Now draw any tile that differs from the way it was last drawn.
+     * An exception is that if either the previous _or_ current state
+     * has the TILE_ROTATING bit set, we must draw it regardless,
+     * because it will have rotated to a different angle.q
+     */
+    for (dy = -1; dy < ds->height+1; dy++) {
+        for (dx = -1; dx < ds->width+1; dx++) {
+            int prev = visible(ds, dx, dy);
+            int curr = todraw(ds, dx, dy);
+            if (prev != curr || ((prev | curr) & TILE_ROTATING) != 0) {
+                draw_tile(dr, ds, dx, dy, curr, angle);
+                visible(ds, dx, dy) = curr;
+            }
+        }
+    }
 
     /*
      * Update the status bar.
diff --git a/apps/plugins/puzzles/src/osx.m b/apps/plugins/puzzles/src/osx.m
index 9d74da1574..be29819b62 100644
--- a/apps/plugins/puzzles/src/osx.m
+++ b/apps/plugins/puzzles/src/osx.m
@@ -687,6 +687,10 @@ struct frontend {
 	if (c >= '0' && c <= '9' && ([ev modifierFlags] & NSNumericPadKeyMask))
 	    c |= MOD_NUM_KEYPAD;
 
+        if (c == 26 &&
+            !((NSShiftKeyMask | NSControlKeyMask) & ~[ev modifierFlags]))
+            c = UI_REDO;
+
 	[self processKey:c];
     }
 }
@@ -735,7 +739,7 @@ struct frontend {
 
 - (void)newGame:(id)sender
 {
-    [self processKey:'n'];
+    [self processKey:UI_NEWGAME];
 }
 - (void)restartGame:(id)sender
 {
@@ -809,11 +813,11 @@ struct frontend {
 }
 - (void)undoMove:(id)sender
 {
-    [self processKey:'u'];
+    [self processKey:UI_UNDO];
 }
 - (void)redoMove:(id)sender
 {
-    [self processKey:'r'&0x1F];
+    [self processKey:UI_REDO];
 }
 
 - (void)copy:(id)sender
diff --git a/apps/plugins/puzzles/src/pattern.c b/apps/plugins/puzzles/src/pattern.c
index 15cdd281c9..270b558bda 100644
--- a/apps/plugins/puzzles/src/pattern.c
+++ b/apps/plugins/puzzles/src/pattern.c
@@ -310,7 +310,18 @@ static void generate(random_state *rs, int w, int h, unsigned char *retgrid)
     fgrid2 = snewn(w*h, float);
     memcpy(fgrid2, fgrid, w*h*sizeof(float));
     qsort(fgrid2, w*h, sizeof(float), float_compare);
-    threshold = fgrid2[w*h/2];
+    /* Choose a threshold that makes half the pixels black. In case of
+     * an odd number of pixels, select randomly between just under and
+     * just over half. */
+    {
+        int index = w * h / 2;
+        if (w & h & 1)
+            index += random_upto(rs, 2);
+        if (index < w*h)
+            threshold = fgrid2[index];
+        else
+            threshold = fgrid2[w*h-1] + 1;
+    }
     sfree(fgrid2);
 
     for (i = 0; i < h; i++) {
@@ -448,6 +459,8 @@ static int do_row(unsigned char *known, unsigned char *deduced,
 
     if (rowlen == 0) {
         memset(deduced, DOT, len);
+    } else if (rowlen == 1 && data[0] == len) {
+        memset(deduced, BLOCK, len);
     } else {
         do_recurse(known, deduced, row, minpos_done, maxpos_done, minpos_ok,
                    maxpos_ok, data, len, freespace, 0, 0);
diff --git a/apps/plugins/puzzles/src/puzzles.h b/apps/plugins/puzzles/src/puzzles.h
index fbfcfce4f8..73b31ea7f9 100644
--- a/apps/plugins/puzzles/src/puzzles.h
+++ b/apps/plugins/puzzles/src/puzzles.h
@@ -47,6 +47,15 @@ enum {
     CURSOR_RIGHT,
     CURSOR_SELECT,
     CURSOR_SELECT2,
+    /* UI_* are special keystrokes generated by front ends in response
+     * to menu actions, never passed to back ends */
+    UI_LOWER_BOUND,
+    UI_QUIT,
+    UI_NEWGAME,
+    UI_SOLVE,
+    UI_UNDO,
+    UI_REDO,
+    UI_UPPER_BOUND,
     
     /* made smaller because of 'limited range of datatype' errors. */
     MOD_CTRL       = 0x1000,
@@ -64,6 +73,7 @@ enum {
 #define IS_CURSOR_MOVE(m) ( (m) == CURSOR_UP || (m) == CURSOR_DOWN || \
                             (m) == CURSOR_RIGHT || (m) == CURSOR_LEFT )
 #define IS_CURSOR_SELECT(m) ( (m) == CURSOR_SELECT || (m) == CURSOR_SELECT2)
+#define IS_UI_FAKE_KEY(m) ( (m) > UI_LOWER_BOUND && (m) < UI_UPPER_BOUND )
 
 /*
  * Flags in the back end's `flags' word.
diff --git a/apps/plugins/puzzles/src/tracks.c b/apps/plugins/puzzles/src/tracks.c
index 0c06c59ae9..578813b1a3 100644
--- a/apps/plugins/puzzles/src/tracks.c
+++ b/apps/plugins/puzzles/src/tracks.c
@@ -1718,7 +1718,10 @@ static void game_changed_state(game_ui *ui, const game_state *oldstate,
 #define TILE_SIZE (ds->sz6*6)
 
 #define BORDER (TILE_SIZE/8)
-#define BORDER_WIDTH (max(TILE_SIZE / 32, 1))
+#define LINE_THICK (TILE_SIZE/16)
+#define GRID_LINE_TL (ds->grid_line_tl)
+#define GRID_LINE_BR (ds->grid_line_br)
+#define GRID_LINE_ALL (ds->grid_line_all)
 
 #define COORD(x) ( (x+1) * TILE_SIZE + BORDER )
 #define CENTERED_COORD(x) ( COORD(x) + TILE_SIZE/2 )
@@ -1738,7 +1741,7 @@ static void game_changed_state(game_ui *ui, const game_state *oldstate,
 #define DS_CSHIFT 20    /* R/U/L/D shift, for cursor-on-edge */
 
 struct game_drawstate {
-    int sz6;
+    int sz6, grid_line_all, grid_line_tl, grid_line_br;
     int started;
 
     int w, h, sz;
@@ -2118,7 +2121,6 @@ static void game_compute_size(const game_params *params, int tilesize,
         int sz6;
     } ads, *ds = &ads;
     ads.sz6 = tilesize/6;
-
     *x = (params->w+2) * TILE_SIZE + 2 * BORDER;
     *y = (params->h+2) * TILE_SIZE + 2 * BORDER;
 }
@@ -2127,6 +2129,9 @@ static void game_set_size(drawing *dr, game_drawstate *ds,
                           const game_params *params, int tilesize)
 {
     ds->sz6 = tilesize/6;
+    ds->grid_line_all = max(LINE_THICK, 1);
+    ds->grid_line_br = ds->grid_line_all / 2;
+    ds->grid_line_tl = ds->grid_line_all - ds->grid_line_br;
 }
 
 enum {
@@ -2346,14 +2351,13 @@ static void draw_square(drawing *dr, game_drawstate *ds,
     /* Clip to the grid square. */
     clip(dr, ox, oy, TILE_SIZE, TILE_SIZE);
 
-    /* Clear the square. */
+    /* Clear the square so that it's got an appropriately-sized border
+     * in COL_GRID and a central area in the right background colour. */
     best_bits((flags & DS_TRACK) == DS_TRACK,
               (flags_drag & DS_TRACK) == DS_TRACK, &bg);
-    draw_rect(dr, ox, oy, TILE_SIZE, TILE_SIZE, bg);
-
-    /* Draw outline of grid square */
-    draw_line(dr, ox, oy, COORD(x+1), oy, COL_GRID);
-    draw_line(dr, ox, oy, ox, COORD(y+1), COL_GRID);
+    draw_rect(dr, ox, oy, TILE_SIZE, TILE_SIZE, COL_GRID);
+    draw_rect(dr, ox + GRID_LINE_TL, oy + GRID_LINE_TL,
+              TILE_SIZE - GRID_LINE_ALL, TILE_SIZE - GRID_LINE_ALL, bg);
 
     /* More outlines for clue squares. */
     if (flags & DS_CURSOR) {
@@ -2389,8 +2393,8 @@ static void draw_square(drawing *dr, game_drawstate *ds,
                            (flags_drag & DS_NOTRACK) == DS_NOTRACK, &c);
     if (flags_best) {
         off = HALFSZ/2;
-        draw_line(dr, cx - off, cy - off, cx + off, cy + off, c);
-        draw_line(dr, cx - off, cy + off, cx + off, cy - off, c);
+        draw_thick_line(dr, LINE_THICK, cx - off, cy - off, cx + off, cy + off, c);
+        draw_thick_line(dr, LINE_THICK, cx - off, cy + off, cx + off, cy - off, c);
     }
 
     c = COL_TRACK;
@@ -2404,8 +2408,8 @@ static void draw_square(drawing *dr, game_drawstate *ds,
             cx += (d == R) ? t2 : (d == L) ? -t2 : 0;
             cy += (d == D) ? t2 : (d == U) ? -t2 : 0;
 
-            draw_line(dr, cx - off, cy - off, cx + off, cy + off, c);
-            draw_line(dr, cx - off, cy + off, cx + off, cy - off, c);
+            draw_thick_line(dr, LINE_THICK, cx - off, cy - off, cx + off, cy + off, c);
+            draw_thick_line(dr, LINE_THICK, cx - off, cy + off, cx + off, cy - off, c);
         }
     }
 
@@ -2426,12 +2430,14 @@ static void draw_clue(drawing *dr, game_drawstate *ds, int w, int clue, int i, i
         cy = CENTERED_COORD(i-w);
     }
 
-    draw_rect(dr, cx - tsz + BORDER, cy - tsz + BORDER,
-              TILE_SIZE - BORDER, TILE_SIZE - BORDER, COL_BACKGROUND);
+    draw_rect(dr, cx - tsz + GRID_LINE_TL, cy - tsz + GRID_LINE_TL,
+              TILE_SIZE - GRID_LINE_ALL, TILE_SIZE - GRID_LINE_ALL,
+              COL_BACKGROUND);
     sprintf(buf, "%d", clue);
     draw_text(dr, cx, cy, FONT_VARIABLE, tsz, ALIGN_VCENTRE|ALIGN_HCENTRE,
               col, buf);
-    draw_update(dr, cx - tsz, cy - tsz, TILE_SIZE, TILE_SIZE);
+    draw_update(dr, cx - tsz + GRID_LINE_TL, cy - tsz + GRID_LINE_TL,
+                TILE_SIZE - GRID_LINE_ALL, TILE_SIZE - GRID_LINE_ALL);
 }
 
 static void draw_loop_ends(drawing *dr, game_drawstate *ds,
@@ -2498,8 +2504,9 @@ static void game_redraw(drawing *dr, game_drawstate *ds, const game_state *oldst
 
         draw_loop_ends(dr, ds, state, COL_CLUE);
 
-        draw_line(dr, COORD(ds->w), COORD(0), COORD(ds->w), COORD(ds->h), COL_GRID);
-        draw_line(dr, COORD(0), COORD(ds->h), COORD(ds->w), COORD(ds->h), COL_GRID);
+        draw_rect(dr, COORD(0) - GRID_LINE_BR, COORD(0) - GRID_LINE_BR,
+                  ds->w * TILE_SIZE + GRID_LINE_ALL,
+                  ds->h * TILE_SIZE + GRID_LINE_ALL, COL_GRID);
 
         draw_update(dr, 0, 0, (w+2)*TILE_SIZE + 2*BORDER, (h+2)*TILE_SIZE + 2*BORDER);
 
diff --git a/apps/plugins/puzzles/src/webpage.pl b/apps/plugins/puzzles/src/webpage.pl
index 3a0779ef0a..c6144bb467 100755
--- a/apps/plugins/puzzles/src/webpage.pl
+++ b/apps/plugins/puzzles/src/webpage.pl
@@ -27,7 +27,7 @@ while (<$desc>) {
         '<span class="puzzle"><table>'.
         '<tr><th align="center">%s</th></tr>'.
         '<tr><td align="center">'.
-        '<img style="margin: 0.5em" alt="" title="%s" width=150 height=150 border=0 src="%s-web.png" />'.
+        '<a href="js/%s.html"><img style="margin: 0.5em" alt="" title="%s" width=150 height=150 border=0 src="%s-web.png" /></a>'.
         '</td></tr>'.
         '<tr><td align="center" style="font-size: 70%%"><code>[</code>'.
         ' <a href="java/%s.html">java</a> '.
@@ -41,6 +41,7 @@ while (<$desc>) {
         '<tr><td align="center">%s</td></tr></table></span>'.
         "\n",
         encode_entities($displayname),
+        encode_entities($id),
         encode_entities($description),
         encode_entities($id),
         encode_entities($id),
diff --git a/apps/plugins/puzzles/src/windows.c b/apps/plugins/puzzles/src/windows.c
index d4b30386a6..ffd0f75894 100644
--- a/apps/plugins/puzzles/src/windows.c
+++ b/apps/plugins/puzzles/src/windows.c
@@ -1545,7 +1545,7 @@ static frontend *frontend_new(HINSTANCE inst)
     fe->statusbar = NULL;
     fe->bitmap = NULL;
 
-    SetWindowLong(fe->hwnd, GWL_USERDATA, (LONG)fe);
+    SetWindowLongPtr(fe->hwnd, GWLP_USERDATA, (LONG_PTR)fe);
 
     return fe;
 }
@@ -1992,7 +1992,7 @@ static void make_dialog_full_screen(HWND hwnd)
 static int CALLBACK AboutDlgProc(HWND hwnd, UINT msg,
 				 WPARAM wParam, LPARAM lParam)
 {
-    frontend *fe = (frontend *)GetWindowLong(hwnd, GWL_USERDATA);
+    frontend *fe = (frontend *)GetWindowLongPtr(hwnd, GWLP_USERDATA);
 
     switch (msg) {
       case WM_INITDIALOG:
@@ -2249,7 +2249,7 @@ static void create_config_controls(frontend * fe)
 static int CALLBACK ConfigDlgProc(HWND hwnd, UINT msg,
 				  WPARAM wParam, LPARAM lParam)
 {
-    frontend *fe = (frontend *)GetWindowLong(hwnd, GWL_USERDATA);
+    frontend *fe = (frontend *)GetWindowLongPtr(hwnd, GWLP_USERDATA);
     config_item *i;
     struct cfg_aux *j;
 
@@ -2260,7 +2260,7 @@ static int CALLBACK ConfigDlgProc(HWND hwnd, UINT msg,
             char *title;
 
 	    fe = (frontend *) lParam;
-	    SetWindowLong(hwnd, GWL_USERDATA, lParam);
+	    SetWindowLongPtr(hwnd, GWLP_USERDATA, lParam);
 	    fe->cfgbox = hwnd;
 
             fe->cfg = frontend_get_config(fe, fe->cfg_which, &title);
@@ -2479,8 +2479,8 @@ static void about(frontend *fe)
 
     SendMessage(fe->cfgbox, WM_SETFONT, (WPARAM)fe->cfgfont, FALSE);
 
-    SetWindowLong(fe->cfgbox, GWL_USERDATA, (LONG)fe);
-    SetWindowLong(fe->cfgbox, DWL_DLGPROC, (LONG)AboutDlgProc);
+    SetWindowLongPtr(fe->cfgbox, GWLP_USERDATA, (LONG_PTR)fe);
+    SetWindowLongPtr(fe->cfgbox, DWLP_DLGPROC, (LONG_PTR)AboutDlgProc);
 
     id = 1000;
     y = height/2;
@@ -2660,8 +2660,8 @@ static int get_config(frontend *fe, int which)
 
     SendMessage(fe->cfgbox, WM_SETFONT, (WPARAM)fe->cfgfont, FALSE);
 
-    SetWindowLong(fe->cfgbox, GWL_USERDATA, (LONG)fe);
-    SetWindowLong(fe->cfgbox, DWL_DLGPROC, (LONG)ConfigDlgProc);
+    SetWindowLongPtr(fe->cfgbox, GWLP_USERDATA, (LONG_PTR)fe);
+    SetWindowLongPtr(fe->cfgbox, DWLP_DLGPROC, (LONG_PTR)ConfigDlgProc);
 
     /*
      * Count the controls so we can allocate cfgaux.
@@ -2975,7 +2975,7 @@ static int is_alt_pressed(void)
 static LRESULT CALLBACK WndProc(HWND hwnd, UINT message,
 				WPARAM wParam, LPARAM lParam)
 {
-    frontend *fe = (frontend *)GetWindowLong(hwnd, GWL_USERDATA);
+    frontend *fe = (frontend *)GetWindowLongPtr(hwnd, GWLP_USERDATA);
     int cmd;
 
     switch (message) {
@@ -2993,18 +2993,18 @@ static LRESULT CALLBACK WndProc(HWND hwnd, UINT message,
 	cmd = wParam & ~0xF;	       /* low 4 bits reserved to Windows */
 	switch (cmd) {
 	  case IDM_NEW:
-	    if (!midend_process_key(fe->me, 0, 0, 'n'))
+	    if (!midend_process_key(fe->me, 0, 0, UI_NEWGAME))
 		PostQuitMessage(0);
 	    break;
 	  case IDM_RESTART:
 	    midend_restart_game(fe->me);
 	    break;
 	  case IDM_UNDO:
-	    if (!midend_process_key(fe->me, 0, 0, 'u'))
+	    if (!midend_process_key(fe->me, 0, 0, UI_UNDO))
 		PostQuitMessage(0);
 	    break;
 	  case IDM_REDO:
-	    if (!midend_process_key(fe->me, 0, 0, '\x12'))
+	    if (!midend_process_key(fe->me, 0, 0, UI_REDO))
 		PostQuitMessage(0);
 	    break;
 	  case IDM_COPY:
@@ -3026,7 +3026,7 @@ static LRESULT CALLBACK WndProc(HWND hwnd, UINT message,
 	    }
 	    break;
 	  case IDM_QUIT:
-	    if (!midend_process_key(fe->me, 0, 0, 'q'))
+	    if (!midend_process_key(fe->me, 0, 0, UI_QUIT))
 		PostQuitMessage(0);
 	    break;
 	  case IDM_CONFIG:
@@ -3405,8 +3405,18 @@ static LRESULT CALLBACK WndProc(HWND hwnd, UINT message,
 	}
 	break;
       case WM_CHAR:
-	if (!midend_process_key(fe->me, 0, 0, (unsigned char)wParam))
-	    PostQuitMessage(0);
+        {
+            int key = (unsigned char)wParam;
+            if (key == '\x1A') {
+                BYTE keystate[256];
+                if (GetKeyboardState(keystate) &&
+                    (keystate[VK_SHIFT] & 0x80) &&
+                    (keystate[VK_CONTROL] & 0x80))
+                    key = UI_REDO;
+            }
+            if (!midend_process_key(fe->me, 0, 0, key))
+                PostQuitMessage(0);
+        }
 	return 0;
       case WM_TIMER:
 	if (fe->timer) {
diff --git a/apps/plugins/puzzles/src/winwix.mc b/apps/plugins/puzzles/src/winwix.mc
index 1a1e620b82..4a72c09123 100644
--- a/apps/plugins/puzzles/src/winwix.mc
+++ b/apps/plugins/puzzles/src/winwix.mc
@@ -61,7 +61,7 @@ has 'descfile' => (required => 1);
 % # (individual files or shortcuts or additions to PATH) that are
 % # installed.
     <Directory Id="TARGETDIR" Name="SourceDir">
-      <Directory Id="ProgramFilesFolder" Name="PFiles">
+      <Directory Id="ProgramFiles64Folder" Name="PFiles">
         <Directory Id="INSTALLDIR" Name="Simon Tatham's Portable Puzzle Collection">
 
 % # The following components all install things in the main