[gtkmm] how to use te signal_focus ?

[Bart Hakvoort <bart hakvoort castel nl>]

I need to check if a Treeview had te focus or not and if it get the
focus i need to know it. So my question is: how do i connect a
signal_focus to a treeview ? 

and another request ;) does anyone have an extended Treeview code? i
have my own ( simple ) treeview now, but i like to do some more
sophisticated things with it. And an example might come in handy

bart