Call this member function to obtain a pointer to the active multiple document interface (MDI) child window of an MDI frame window.
virtual CFrameWnd* GetActiveFrame( );
A pointer to the active MDI child window. If the application is an SDI application, or the MDI frame window has no active document, the implicit this pointer will be returned.
If there is no active MDI child or the application is a single document interface (SDI), the implicit this pointer is returned.