Value Meaning
HWND_BOTTOM Places the window at the bottom of the Z order. If the hWnd parameter identifies a topmost window, the window loses its topmost status and is placed at the bottom of all other windows.
HWND_NOTOPMOST Places the window above all non-topmost windows (that is, behind all topmost windows). This flag has no effect if the window is already a non-topmost window.
HWND_TOP Places the window at the top of the Z order.
HWND_TOPMOST Places the window above all non-topmost windows. The window maintains its topmost position even when it is deactivated.