libgtk-3-dev seems to break Ubuntu 12.04 LTS Unity Interface

[David Buchan <pdbuchan yahoo com>]

Hi,

I've been using Ubuntu 10.04 and libgtk2.0-dev and glade for a long time and recently attempted to bring myself into the present by doing a fresh install of 12.04 LTS.

But once I installed libgtk-3-dev and glade from the repository, I wasn't able to log back into the computer unless I typed cntl-alt-F1 and went to TTY. The graphical login screen accepts my credentials but then the screen very briefly shows a broken pipe message at the top-left of a TTY screen and then the login screen re-appears.

Scouring the web shows that many people have similar problems, but that there are many possible causes. I tried a number of solutions and one that allows me to get past the login while still in a graphical session, is to first go to TTY and sudo aptitude install gnome-panel. The problem with this solution is that Unity isn't rendered properly and is really unusable.

I *think* I saw that when I installed libgtk-3-dev, all kinds of gnome stuff is removed. Anway, it was either libgtk-3-dev or glade, because that's all I installed after the OS was installed.

I had tried going to a newer Ubuntu last year with the same results (maybe different cause?), so I stayed with 10.04. What's really extraordinary, is that last night I re-installed 10.04 when 12.04 failed as described above, and now 10.04 has the same problem (but with libgtk2.0-dev and glade)! Could it be that those libgtk packages have recently been changed and broke the Ubuntu interface? Seems unlikely.

Has anybody got suggestions and how to approach this? I saw some people talking about lightdm versus gdm. I also tried that (uninstall lightdm, install gdm), but *if* I recall (it was a late late night) although I got past login, Unity was all buggered with that too.

Dave