BOOL SetWindowPos(HWND hWnd , HWND hWndlnsertAfter , int X , int Y , int cx , int cy , UNIT uFlags);这个吧
hWndInsertAfter [in] Handle to the window to precede the positioned window in the Z order. This parameter must be a window handle or one of the following values. 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.
[in] Handle to the window to precede the positioned window in the Z order. This parameter must be a window handle or one of the following values. 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.