- move paint to idle handlers
- finish the multiple selection code for lists (check for add handlers for 
  scrolling while drag-selecting).
- check whether WMDestroyWidget() should first call WMUnmapWidget().
- check if its useful to add some WMBrowserSelectionDidChangeNotification
  (actually a pass-through for WMListSelectionDidChangeNotification).
  Or a delegate to be called when the list selection change.


- optimize color allocation for repeated colors
- make it work in 8bpp
- optimize SystemFont allocation for repeated font sizes