Probably a little off-topic? There are glade and gtk lists, groups,
forums, irc channels that specialise in this type of thing.
Just try searching, there's tons of stuff out there, and tons (and
tons) of code. Although code with complex examples don't teach you
much.
e.g. first result on google: http://live.gnome.org/Glade/Tutorials
Don't waste your money or time on books which will just be out of date
at best.
Apart from the layout managers which take a little while to get used
to (to create exactly what you want), it's pretty straightforward.
To be honest, for such types of software, nothing works as well as
just firing it up and playing with it, and only look up a reference
when you can't work out how to do something you think you should be
able to.
!Z