The frame of the Window resizes separately from its controls; the controls 
resize only when the mouse is released.

Repro steps:
1. Bring up Pan.
2. Resize main window.

Result:
Frame is resized; child controls are not.

Expected result:
Layout of child controls updates and is repainted with the frame window.

Possible flaw/solution:
Looks like WM_EXITSIZEMOVE is being used to relayout the controls in the 
window. WM_SIZE should be used to relayout the controls instead. Care 
should be taken to ensure that the layout code will not crash with a main 
window width of zero (which will occur at the end of the window being 
minimized).