I'm talking about the change from Gtk1.0 to Gtk2.0 (or that's what I remember mostly). I gave up on Gentoo around 2001 or so. Things were better when I left, but there was still breakage whenever I did a world-update. I had fallen into the lazy habit of not updating often enough which contributed to the problem, but still, the promise was that all you had to do was to do a world-update and everything would work fine. Maybe it does now, but I remember having to run a crippled system for a couple of weeks at a time, while trying to sort through the numerous broken packages. I had used many different desktops including XFCE. They were all pretty good and completely flexible under Gentoo, as the Desktop designers had intended. That part was fine, but the underlying Gtk libraries were a complete PITA whenever there were large changes.