Not that it in any way disproves your post, but Emacs does use GTK+.
I'm sorry about my post, and I can't edit it. It was trolled, and this thread shouldn't dissolve into a silly flamewar.
I think that GTK is a good toolkit, and will always be an important part of the GNU/Linux/*nix ecosystem.
It's just depressing to see that the "Kill KDE ayatollahs" from the dark ages of desktop wars are still alive. Qt is a fantastic toolkit used by some of the best Linux software: VLC, Amarok, SMPlayer, even Skype.
The most important Linux apps which made it viable for a desktop are neither Qt nor GTK anyway: OpenOffice and Firefox. Same goes for Thunderbird and other Mozilla stuff. The most important editors are neither: Emacs and vim (despite vim's optional menubar which is not needed).
Not that it in any way disproves your post, but Emacs does use GTK+.
I might be stuck in the past... Does XEmacs use it too?
I'm not really sure, some sort of GTK+ support seems to exist for XEmacs, but I don't think it's used by default?
I personally like using fox, although naturally that, like qt, is for C++. One thing that gtk has is working entirely with C. Just wanted to point that out.
Sorry but that is a myth. None said there would be a _total_ rewrite. Yeah binary compatibility and API will be broken at _some_ areas yet not at all. That would make no sense.
The idea of such changes is to remove old cruft, add new stuff where it was not possible before. As well to rearange stuff if it turned out to be far from ideal.
Same was true for KDE 4.0.
Yeah I'd like it if Gnome was written in Qt, yet that is just an illusion that won't come true. It would just take too much work for gains that would not justify that. Plain simple: Gnome works pretty well with GTK+ already so rather improve GTK+ than to start over.
Apps *don't* need to be ported to Gtk+ 3.x, as long as they're already coded to "best practices" for Gtk+ 2.x - i.e not using any of the deprecated API that's being removed, not accessing 'private' data directly, etc. As far as I can tell, well-written code should be compilable against either version.
GTK 3.x breaks ABI/API; slightly. It got rid of a bunch of old crusty features that turned out to not be popular and is introduced new frameworks to replace them. (Ie. Dbus for Corba)
But distributions can still maintain compatibility with older applications as long as they want without to much effort.
And, btw, the KDE 3.5.x transition to KDE 4.0 is the posterboy for what not to do. It's one of the best things that ever happened to Gnome, in terms of aiding in it's popularity.