in reply to Advice on writing GUI's in Perl
Lots of questions! I have some answers, but first, you should know about the gtk-perl list. The gtkperl website is out of date. gtk-perl now supports Gtk+ 2 and there are bindings (announced today) for the development version. gtk-perl is at 1.0, IIRC. There is a whole directory of examples with the distro.
You can use Glade and proably any tools that talk to glade (I have not tried the ones you mention) to generate code that works with gtk-perl. I understand the easiest way is to generate the XML with glade, then read that into your perl program. Again, I have not tried it, but there has been discussion on the list and you should check the archives at the link noted above.
To answer some of your specific questions, Gtk+ exists on Linux and Windows. A Win32 version of the perl bindings should be out any time now. You do not need Gnome for Gtk+. You do need Gnome if you use Gnome features (i.e. you use Gnome widgets in your design).
HTH, --traveler
In Section
Seekers of Perl Wisdom