diff --git a/firmware/drivers/button_queue.c b/firmware/drivers/button_queue.c
index 1679fc224e..f539b88b75 100644
--- a/firmware/drivers/button_queue.c
+++ b/firmware/drivers/button_queue.c
@@ -24,6 +24,7 @@
 #include "button.h"
 #ifdef HAVE_SDL
 #include "button-sdl.h"
+#include "lcd-sdl.h"
 #endif
 
 static struct event_queue button_queue SHAREDBSS_ATTR;
@@ -100,7 +101,7 @@ static inline void button_queue_wait(struct queue_event *evp, int timeout)
     unsigned long curr_tick, remaining;
     while(true)
     {
-        handle_sdl_events();
+        handle_sdl_events(); /* Includes window updates after resize events */
         queue_wait_w_tmo(&button_queue, evp, TIMEOUT_NOBLOCK);
         if (evp->id != SYS_TIMEOUT || timeout == TIMEOUT_NOBLOCK)
             return;
@@ -117,6 +118,9 @@ static inline void button_queue_wait(struct queue_event *evp, int timeout)
     }
 #else
     queue_wait_w_tmo(&button_queue, evp, timeout);
+#ifdef HAVE_SDL
+    sdl_update_window(); /* Window may have been resized */
+#endif
 #endif
 }
 #endif /* HAVE_ADJUSTABLE_CPU_FREQ */
diff --git a/firmware/target/hosted/sdl/button-sdl.c b/firmware/target/hosted/sdl/button-sdl.c
index 621b63f930..0ba54d064a 100644
--- a/firmware/target/hosted/sdl/button-sdl.c
+++ b/firmware/target/hosted/sdl/button-sdl.c
@@ -31,6 +31,7 @@
 #include "backlight.h"
 #include "system.h"
 #include "button-sdl.h"
+#include "lcd-sdl.h"
 #include "sim_tasks.h"
 #include "buttonmap.h"
 #include "debug.h"
@@ -240,6 +241,17 @@ static bool event_handler(SDL_Event *event)
             sdl_app_has_input_focus = 1;
         else if (event->window.event == SDL_WINDOWEVENT_FOCUS_LOST)
             sdl_app_has_input_focus = 0;
+        else if(event->window.event == SDL_WINDOWEVENT_RESIZED)
+        {
+            sdl_window_needs_update();
+#if !defined (__APPLE__) && !defined(__WIN32)
+            static unsigned long last_tick;
+            if (TIME_AFTER(current_tick, last_tick + HZ/20) && !button_queue_full())
+                  button_queue_post(SDLK_UNKNOWN, 0); /* update window on main thread */
+            else
+                  last_tick = current_tick;
+#endif
+        }
         break;
     case SDL_KEYDOWN:
     case SDL_KEYUP:
diff --git a/firmware/target/hosted/sdl/lcd-sdl.c b/firmware/target/hosted/sdl/lcd-sdl.c
index 1e9daeffd3..2e4caa7edc 100644
--- a/firmware/target/hosted/sdl/lcd-sdl.c
+++ b/firmware/target/hosted/sdl/lcd-sdl.c
@@ -23,9 +23,99 @@
 #include "lcd-sdl.h"
 #include "sim-ui-defines.h"
 #include "system.h" /* for MIN() and MAX() */
+#include "misc.h"
 
 double display_zoom = 1;
 
+static bool window_needs_update;
+
+void sdl_get_window_dimensions(int *w, int *h)
+{
+    if (background)
+    {
+        *w = UI_WIDTH;
+        *h = UI_HEIGHT;
+    }
+    else
+    {
+#ifdef HAVE_REMOTE_LCD
+        if (showremote)
+        {
+            *w = SIM_LCD_WIDTH > SIM_REMOTE_WIDTH ? SIM_LCD_WIDTH : SIM_REMOTE_WIDTH;
+            *h = SIM_LCD_HEIGHT + SIM_REMOTE_HEIGHT;
+        }
+        else
+#endif
+        {
+            *w = SIM_LCD_WIDTH;
+            *h = SIM_LCD_HEIGHT;
+        }
+    }
+}
+
+static inline void sdl_render(void)
+{
+    SDL_Texture *sdlTexture = SDL_CreateTextureFromSurface(sdlRenderer, gui_surface);
+    SDL_RenderClear(sdlRenderer);
+    SDL_RenderCopy(sdlRenderer, sdlTexture, NULL, NULL);
+    SDL_RenderPresent(sdlRenderer);
+    SDL_DestroyTexture(sdlTexture);
+}
+
+
+#define SNAP_MARGIN 50
+int sdl_update_window(void)
+{
+    if (!window_needs_update)
+        return false;
+    window_needs_update = false;
+
+#if defined (__APPLE__) || defined(__WIN32) /* Constrain aspect ratio */
+    if (!(SDL_GetWindowFlags(window) & (SDL_WINDOW_MAXIMIZED | SDL_WINDOW_FULLSCREEN)))
+    {
+        float aspect_ratio;
+        int w, h;
+
+        sdl_get_window_dimensions(&w, &h);
+        aspect_ratio = (float) h / w;
+
+        int original_height = h;
+        int original_width = w;
+
+        SDL_GetWindowSize(window, &w, &h);
+        if (w != original_width || h != original_height)
+        {
+            if (abs(original_width - w) < SNAP_MARGIN)
+            {
+                w = original_width;
+                h = original_height;
+            }
+            else
+                h = w * aspect_ratio;
+
+            SDL_SetWindowSize(window, w, h);
+        }
+    }
+#endif
+    sdl_render();
+    return true;
+}
+
+void sdl_window_needs_update(void)
+{
+    window_needs_update = true;
+
+    /* For MacOS and Windows, we're on a main or
+    display thread already, and can immediately
+    update the window.
+    On Linux, we have to defer the update, until
+    it is handled by the main thread later. */
+#if defined (__APPLE__) || defined(__WIN32)
+    sdl_update_window();
+#endif
+}
+
+
 void sdl_update_rect(SDL_Surface *surface, int x_start, int y_start, int width,
                      int height, int max_x, int max_y,
                      unsigned long (*getpixel)(int, int))
@@ -117,15 +207,12 @@ void sdl_gui_update(SDL_Surface *surface, int x_start, int y_start, int width,
 
     uint8_t alpha;
     if (SDL_GetSurfaceAlphaMod(surface,&alpha) == 0 && alpha < 255)
-        SDL_FillRect(gui_surface, &dest, 0);
+        SDL_FillRect(gui_surface, &dest, 0); /* alpha needs a black background */
 
-    SDL_BlitSurface(surface, &src, gui_surface, &dest); /* alpha needs a black background */
+    SDL_BlitSurface(surface, &src, gui_surface, &dest);
 
-    SDL_Texture *sdlTexture = SDL_CreateTextureFromSurface(sdlRenderer, gui_surface);
-    SDL_RenderClear(sdlRenderer);
-    SDL_RenderCopy(sdlRenderer, sdlTexture, NULL, NULL);
-    SDL_RenderPresent(sdlRenderer);
-    SDL_DestroyTexture(sdlTexture);
+    if (!sdl_update_window()) /* already calls sdl_render itself */
+        sdl_render();
 }
 
 /* set a range of bitmap indices to a gradient from startcolour to endcolour */
diff --git a/firmware/target/hosted/sdl/lcd-sdl.h b/firmware/target/hosted/sdl/lcd-sdl.h
index 3f1334e4a2..17fa6e192e 100644
--- a/firmware/target/hosted/sdl/lcd-sdl.h
+++ b/firmware/target/hosted/sdl/lcd-sdl.h
@@ -28,6 +28,11 @@
 /* Default display zoom level */
 extern SDL_Surface *gui_surface;
 extern SDL_Renderer *sdlRenderer;
+extern SDL_Window *window;
+
+void sdl_get_window_dimensions(int *w, int *h);
+int sdl_update_window(void);
+void sdl_window_needs_update(void);
 
 void sdl_update_rect(SDL_Surface *surface, int x_start, int y_start, int width,
                      int height, int max_x, int max_y,
diff --git a/firmware/target/hosted/sdl/system-sdl.c b/firmware/target/hosted/sdl/system-sdl.c
index e1c00a3915..e18bbd779c 100644
--- a/firmware/target/hosted/sdl/system-sdl.c
+++ b/firmware/target/hosted/sdl/system-sdl.c
@@ -91,28 +91,7 @@ static void sdl_window_setup(void)
         }
     }
 
-    /* Set things up */
-    if (background)
-    {
-        width = UI_WIDTH;
-        height = UI_HEIGHT;
-    }
-    else
-    {
-#ifdef HAVE_REMOTE_LCD
-        if (showremote)
-        {
-            width = SIM_LCD_WIDTH > SIM_REMOTE_WIDTH ? SIM_LCD_WIDTH : SIM_REMOTE_WIDTH;
-            height = SIM_LCD_HEIGHT + SIM_REMOTE_HEIGHT;
-        }
-        else
-#endif
-        {
-            width = SIM_LCD_WIDTH;
-            height = SIM_LCD_HEIGHT;
-        }
-    }
-
+    sdl_get_window_dimensions(&width, &height);
     depth = LCD_DEPTH;
     if (depth < 8)
         depth = 16;
@@ -122,11 +101,20 @@ static void sdl_window_setup(void)
     flags |= SDL_WINDOW_FULLSCREEN;
 #endif
 
+    if (display_zoom == 1)
+        flags |= SDL_WINDOW_RESIZABLE;
+
+    flags |= SDL_WINDOW_ALLOW_HIGHDPI;
+
     if ((window = SDL_CreateWindow(UI_TITLE, SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
                       width * display_zoom, height * display_zoom , flags)) == NULL)
         panicf("%s", SDL_GetError());
     if ((sdlRenderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_PRESENTVSYNC)) == NULL)
         panicf("%s", SDL_GetError());
+
+    SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, "linear");
+    SDL_RenderSetLogicalSize(sdlRenderer, width * display_zoom, height * display_zoom);
+
     if ((gui_surface = SDL_CreateRGBSurface(0, width * display_zoom, height * display_zoom, depth,
                                        0, 0, 0, 0)) == NULL)
         panicf("%s", SDL_GetError());
@@ -152,6 +140,7 @@ static void sdl_window_setup(void)
 static int sdl_event_thread(void * param)
 {
 #ifdef __WIN32 /* Fails on Linux and MacOS */
+    SDL_SetHint(SDL_HINT_WINDOWS_DPI_SCALING, "1");
     SDL_InitSubSystem(SDL_INIT_VIDEO);
     sdl_window_setup();
 #endif