Determines which, if any, of the child windows belonging to the specified parent window contains the specified point
_WinAPI_ChildWindowFromPointEx ( $hWnd, $tPOINT [, $iFlags = 0] )
|$hWnd||Handle to the parent window.|
|$tPOINT||$tagPOINT structure that defines the client coordinates (relative to hwndParent) of the point to be checked.|
|$iFlags||[optional] The flags that specify which child windows to skip. This parameter can be one or more of the following values:
|Success:||Handle to the first child window. If the point is within the parent window but not within any child window that meets the criteria, the return value is a handle to the parent window. If the point lies outside the parent window, the return value is 0.|
The system maintains an internal list that contains the handles of the child windows associated with a parent window.
The order of the handles in the list depends on the Z order of the child windows.
If more than one child window contains the specified point, the system returns a handle to the first window in the list that contains the point and meets the criteria specified by $iFlags.
Search ChildWindowFromPointEx in MSDN Library.