Important:
  ocemgpui.widgets:
    - Improve layer notifications.
    - Speed up drawing/updates.

Should be done later:
  - Add generic drag'n' drop features.

  ocempgui.draw:
    - Add cairo support (as C module?) for text and anything else.

  ocempgui.widgets:
    - Add border blinking for hidden (overlayed) objects.
    - Add configuration loader for users.
    - Add keyboard control to ImageMap.
    - More image files.
    - Menu widgets for interactive menus.
    - Add support for copy and paste operations.
    - Add TextView class for multiline editing.
    - Add text selections.
    - Add optional alpha transparency for non-active layers.
 
Nice to have:
  ocempgui.widgets, ocempgui.draw:
    - Add more intelligent style caches to speed up drawing.

  ocempgui.widgets:
    - bidirectional support for widgets.