Gtk.Window.prototype.set_keep_below

function set_keep_below(setting:Boolean):void {
    // Gjs wrapper for gtk_window_set_keep_below()
}

Asks to keep window below, so that it stays in bottom. Note that you shouldn't assume the window is definitely below afterward, because other entities (e.g. the user or <link linkend="gtk-X11-arch">window manager</link>) could not keep it below, and not all window managers support putting windows below. But normally the window will be kept below. Just don't write code that crashes if not.

It's permitted to call this function before showing a window, in which case the window will be kept below when it appears onscreen initially.

You can track the below state via the "window-state-event" signal on Gtk.Widget.

Note that, according to the <ulink url="http://www.freedesktop.org/Standards/wm-spec">Extended Window Manager Hints</ulink> specification, the above state is mainly meant for user preferences and should not be used by applications e.g. for drawing attention to their dialogs.

Since 2.4