Indicates whether the window specified by pWnd is a child window or other direct descendant of CWnd.
BOOL IsChild( const CWnd* pWnd ) const;
Identifies the window to be tested.
Specifies the outcome of the function. The value is nonzero if the window identified by pWnd is a child window of CWnd; otherwise 0.
A child window is the direct descendant of CWnd if the CWnd object is in the chain of parent windows that leads from the original pop-up window to the child window.