[gtkmm] Getting notfified when window opens on display?

[Toralf Lund <toralf procaptura com>]

Actually, I think I'll rephrase the question from earlier today... I
might have asked:

Is there a way I can setup gtkmm so that my app is notified whenever a
new window is opened on the current display?

With XLib you can do this by checking for "Substructure" events
(SubstructureNotifyMask) of type "CreateNotify" on the root window. In
other words, if I can catch an XLib event in general, the problem is
probably solved, but I'm open to other solutions, too.

- Toralf