Is there any GUI layout builder tools? Like qtbuilder?
Uh, if you use gtk2 you can use glade. That really has nothing to do with Perl, though, except that the Perl API supports the same features of gtk2 that the C API does.
Thank you for pointing to Glade. It looks like that GTK2 is the best way to go with desktop apps and perl now. Just make sure you look at Gtk2 module, not Gtk (this one was never updated and linked against old GTK library).