Allow to overwrite draw function per widget

docs/index.rst

@@ -111,6 +111,9 @@ The following code will create this UI:
         -- nested content, whichever is bigger
         suit.layout:push(suit.layout:row())
 
+            -- change cell padding to 3 pixels in either direction
+            suit.layout:padding(3)
+
             -- put a slider in the cell
             -- the inner cell will be 160 px wide and 20 px high
             suit.Slider(slider, suit.layout:col(160, 20))

docs/layout.rst

@@ -116,7 +116,7 @@ Used to provide the last four arguments to a widget, e.g.::
 
 
 Precomputed Layouts
-------------------
+-------------------
 
 Apart from immediate mode layouts, you can specify layouts in advance.
 The specification is a table of tables, where each inner table follows the

docs/widgets.rst

@@ -164,8 +164,10 @@ Common Options
    ``"bottom"``. Defaults to ``"middle"``.
 
 ``color``
-   Table overwriting the color. Undefined colors default to the theme colors.
+   A table to overwrite the color. Undefined colors default to the theme colors.
 
+``draw``
+   A function to replace the drawing function. Refer to :doc:`themes` for more information about the function signatures.
 
 
 Common Return States