HWND real?

[Dennis Bjorklund]

I want to test the parameter hFocusTo in

void FOCUS_SwitchFocus( MESSAGEQUEUE *pMsgQ,
                        HWND hFocusFrom, HWND hFocusTo )

and see if it really is a window. I would like to put out an warning or
error in that case. Is there some debug-function I can use that can check
that a HWND really is a real window handle.

-- 
/Dennis