This function determines which, if any, of the child windows belonging to a parent window contains the specified point.
A handle to the child window that contains the point, even if the child window is hidden or disabled, indicates success. A handle to the parent window indicates that the point is within the parent window but not within any child window. A handle to the parent window can also indicate that the point is in the non-client area.
The ChildWindowFromPoint function is conditionally included in the Winuser.h file if the Windows Embedded CE operating system is built to contain include files and import libraries from Microsoft® Platform Builder.
The system maintains an internal list, containing 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.