void gtk_window_set_keep_below ( GtkWindow* window, gboolean setting )
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
[window manager][gtk-X11-arch]) 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
Note that, according to the Extended Window Manager Hints 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.