Lowers this window to the bottom of the Z-order (stacking order), so that other windows with the same parent window appear above this window. This is true whether or not the other windows are visible. If this window is a toplevel, the window manager may choose to deny the request to move the window in the Z-order, Gtk.Window.Lower only requests the restack, but does not guarantee it. Note that Window.Show raises the window again, so don't call this function before Window.Show. (Try Window.ShowUnraised.)