[GD-Windows] Detecting mouse exiting window?

[Brian H. <bri...@py...>]

Is there a clean way of detecting when the mouse cursor has exited my
window?  WM_MOUSEMOVE and WM_NCMOUSEMOVE messages stop coming in the
moment the mouse exits the window.  The only other thing I can think of
is to actually poll the mouse position and see if it's in my client area
(blech).

Brian