Claims the input focus.
CWnd* SetFocus( );
A pointer to the window object that previously had the input focus. It is NULL if there is no such window. The returned pointer may be temporary and should not be stored.
The input focus directs all subsequent keyboard input to this window. Any window that previously had the input focus loses it.
The SetFocus member function sends a WM_KILLFOCUS message to the window that loses the input focus and a WM_SETFOCUS message to the window that receives the input focus. It also activates either the window or its parent.