Thanks to Tim-Philipp Müller for writing such wonderful source material, and for answering my questions in #gtk+.
And of course thanks to the entire Ruby-GNOME2 team.
Thanks to Axel C. for proof-reading the first drafts, for many suggestions, and for introducing me to the tree view widget in the first place (back then when I was still convinced that porting to Gtk+-2.x was unnecessary, Gtk+-1.2 applications looked nice, and Aristotle had already said everything about politics that needs to be said).
Harring Figueiredo shed some light on how GtkListStore and GtkTreeStore deal with pixbufs.
Ken Rastatter suggested some additional topics (with complete references even).
Many thanks to all of them, and of course also to kris and everyone else in #gtk+.