Genau weiß ich es auch nicht. Aber ist das nicht die z-Order? dann kuck dir mal in deiner Anwendung WM_ACTIVATE an:
Zitat:
wParam
The low-order word specifies whether the window is being activated or deactivated. This parameter can be one of the following values. The high-order word specifies the minimized state of the window being activated or deactivated. A nonzero value indicates the window is minimized.
WA_ACTIVE
Activated by some method other than a mouse click (for example, by a call to the SetActiveWindow function or by use of the keyboard interface to select the window).
WA_CLICKACTIVE
Activated by a mouse click.
WA_INACTIVE
Deactivated.
lParam
Handle to the window being activated or deactivated, depending on the value of the wParam parameter. If the low-order word of wParam is WA_INACTIVE, lParam is the
handle to the window being activated. If the low-order word of wParam is WA_ACTIVE or WA_CLICKACTIVE, lParam is the
handle to the window being deactivated. This
handle can be NULL.