Lowers the window to the bottom of the Z-order (stacking order), so that other windows with the same parent window appear above the window. If the window is a toplevel, the window manager may choose to deny the request to move the window in the Z-order. Therefore, the lower() method only requests the restack, it does not guarantee it.

Note that the show() method raises the window again, so don't call this method before calling the show() method to avoid duplication.