I also can confirm this error on gutsy with:
$ ruby -r gtk2 -e 'p Gtk::VERSION' [2, 12, 0] $ ruby --version ruby 1.8.6 (2007-06-07 patchlevel 36) [i486-linux] $ uname -r 2.6.22-14-generic
Also here Andy Owen's patch fixes the problem.
I also can confirm this error on gutsy with:
$ ruby -r gtk2 -e 'p Gtk::VERSION'
[2, 12, 0]
$ ruby --version
ruby 1.8.6 (2007-06-07 patchlevel 36) [i486-linux]
$ uname -r
2.6.22-14-generic
Also here Andy Owen's patch fixes the problem.