overlapping windows

Hi, we are developing an OpenGL ES application running on Windows CE. The window where OpenGL ES paints on is partially occluded by other windows. It seems Window's clip regions are not respected, because I always get the whole rectangular region of window shown on the display, painted by OpenGL ES.


I even did an experiment, where a child window is partially outside its parent window. I could even have it painted outside the parent window by painting on the chilld window using OpenGL ES.

 

Question: Is it a known behavior?

 

Thanks.