wxMDIParentFrame *mdiParent = (wxMDIParentFrame *)GetParent();
::ScreenToClient((HWND) mdiParent->GetClientWindow()->GetHWND(), &point);
wxMDIParentFrame *mdiParent = (wxMDIParentFrame *)GetParent();
::ScreenToClient((HWND) mdiParent->GetClientWindow()->GetHWND(), &point);