CWnd::accHitTest
Visual Studio 2010
Called by the framework to retrieve the child element or child object at a given point on the screen.
virtual HRESULT accHitTest( long xLeft, long yTop, VARIANT *pvarChild );
This function is part of MFC's Active Accessibility support.
Override this function in your CWnd-derived class if you have nonwindowed user interface elements (other than windowless ActiveX controls, which MFC handles).
For more information, see IAccessible::accHitTest in the Windows SDK.