窗口收不到WM_MOUSELEAVE

 想要收到WM_MOUSELEAVE，需要在合适的时机调用_TrackMouseEvent（如WM_MOUSEMOVE）

TRACKMOUSEEVENT t = {sizeof(TRACKMOUSEEVENT),TME_LEAVE,m_hWnd,0};if (::_TrackMouseEvent(&t)){ //InvalidateRect(NULL);}