any window (or whatever) signal precursor to focus in/out of widget ?

[Nicolas Jäger <jagernicolas legtux org>]

Hi
I use a `treeview` when I click on a line I want to save the current
work I made for the last line selected. The problem, I got "focus
in" signal emited before "focus out". So I wonder if there is
any signal wich can detect that the focus is going to change. So I can
(for example) popup a window and asking the user if it is really what he
wants to do.

regards,
Nicolas J.