Opens a WinWatch context for monitoring window overlap.
HWINWATCH FAR PASCAL _loadds WinWatchOpen(hwnd);HWND hwnd;INPUT PARAMETERS
hwnd
Handle of a window with which this WinWatch context will be associated.
RETURNS
Returns a handle of type HWINWATCH corresponding to a WinWatch context.
COMMENTS
If the window handle changes, WinWatchOpen must be called again with the new handle.