Gtk::SourceView still supported?

_editor.rb:485:in text_field': undefined methodset_show_line_markers’
for #<Gtk::SourceView:0x7f3e4ec12ff8 ptr=0x262c030> (NoMethodError)

I have a few problems getting SourceView to work.

(a) Is one of you using it with the latest ruby-gnome release? And if
so, could you tell me your versions of GTK and ruby?

Right now I use GTK: 2.24.5 and Ruby: ruby 1.8.7 (2011-02-18 patchlevel
334) [x86_64-linux]