Hi,
I process WM_ERASEBKGND message for WS_CHILD window:
Code:
  case WM_ERASEBKGND:
     GetUpdateRect(hWnd,&urect,FALSE);
    //...........
In urect i always get {0,0,0,0}. That's why I ask: does DefWindowProc while processing WM_ERASEBKGND use update region or erase entire client area?