Why am I stuck with a version of GNOME Shell unlike KDE? For example, on Ubuntu 12.04 I am stuck with GNOME Shell version 3.4, and I can't upgrade to a newer version of GNOME Shell like 3.6.
With Kubuntu 12.04 comes with KDE 4.8 and I can upgrade it to the latest version which is 4.10. It seems like if a version of GNOME Shell gets released after a version of Ubuntu, it does support that version of Ubuntu. Does anyone know why it is like this? Does this have something to do with GTK dependencies?
There's a few reasons for this, and it probably comes down to packaging and 'stability'. On a mainstream distribution, its more important to have a system that works reliably than to have the latest packages - as such they often freeze on a major version and add updates gradually.
These days kubuntu is maintained by one of the organisations that develops KDE and they can spend the resources integrating more recent versions. On the other hand, Ubuntu uses unity, and gnome 3 isn't really one of the mainline DEs supported by various derivative teams.
You could, however, at your own risk, upgrade to a newer version of gnome shell though a PPA. Gnome3's Website mentions these risks - regressions, and links to a staging repo with newer packages. Things can break