GUIBaseContext :: doAfterMouseMove - Post-event handler for mose move events

The post-event handler for mouse move events (GEV_MouseMove) allows e.g. manipulating the mouse pointer. Successive events are generated while moving the mouse. Thus, mouse move handler should be handled with care in order to avoid performance problems. The current mouse position can be provided by calling GetMousePosition().

The handler should return one of the following return codes:

• -1 (not handled) - the event handler will be removed from the handler list and is not called anymore.
• 1 (error) - Returning an error has no effect for post-events.
• 0 (ok) - Event handler terminated successfully.