Window Manager changes
----------------------

When the pointer idles at the edge of the screen, a message is sent to
all tasks. Presently this message relies on the iconbar toggle being
enabled. Future versions may not have this restriction.

Message_ScreenEdgeNotification (&400D2)

 R1+16  = &400D2
 R1+20  = bit mask :
            0    left of screen
            1    bottom of screen
            2    right of screen
            3    top of screen
          others reserved

This message is sent by the WindowManager when the pointer idles over the
edge of the screen. It is intended that shortcut applications might use
this to activate themselves.
