But that isn't very helpful nor really that useful. Computers aren't single purpose appliances (even if some people treat them like that but even in that case,

But that isn't very helpful nor really that useful. Computers aren't single purpose appliances (even if some people treat them like that but even in that case, they tend to have different opinion about what sort of appliances they are). Ubuntu (and i guess Fedora) out of the box isn't that useful and the moment you install anything that wasn't made with, say, Gtk3 in mind things start to crack. Actually i think in Ubuntu you do not even need to install anything, just open the web browser and things start to not mesh that nicely. And IMO if anything, the reason you get all those different behaviors is exactly because things break. If Gtk3 was backwards compatible with Gtk2 (in a fantasy world where the Gtk developers did learn from the mistakes of Gtk1 to Gtk2 breakage and designed their Gtk2 APIs to avoid it in the future) then all Gtk2 applications would gain, if not all, then at least some of the new functionality in Gtk3. Programs that were abandoned would still get some of the new stuff while programs that are under development would be able to keep using whatever they are using and upgrade in their own pace only the minor differences that were needed for the new functionality.