Application is hung when calling AccessibleObjectFromPoint

Hello all,

I have an application need to retrieve the control information base on calling AccessibleObjectFromPoint. However, when I call this API, sometimes the targeted application is hung if the point is the center point of window, but if I set another point, then targeted application is not hung at all.

Does anyone know why some application hangs when I call this API? And how can we avoid hanging issue? 

Thanks.