code cleanup
fixed altk_widget_map()
fixed size negotiation
created the widget's window
fixed window bounds in Dialog.size_allocate()
set the NOWINDOW flag on AltkLabel
fixed Widget.realize() for nowindow widgets
fixed Window parent/children and coordinates
generated the EXPOSE event for windows
fixed Window base class
added the global event handler
fixed altk_event_process()
fixed widget event handling
recursively called child widgets on expose event
added Window.update_area
added a TODO remainder
fixed area on expose events
clipped expose area for each widget
code cleanup
fixed Widget.map()