I am almost new to Ubuntu 14.04 (64 bits, in my case) so I only know the Unity interface and a bit of Gnome from previous Ubuntu experience. As the new version of KDE looked promising, I installed kde-desktop thinking I would automatically get whatever display manager allowing me to choose between KDE and Unity at boot time.
Unfortunately no display manager ever showed up (nor even by clicking on the small icon supposed to do that at login time, which looked dead) and I seemed to be stuck on KDE (very nice, but totally unfamiliar to me, so while I am learning to tune KDE, I just HAVE to go on with my normal work for at least some months with Unity).
Reinstalling ubuntu-desktop made things even worse : automatic login gives me a black screen. Of coures, I can still kill the server from a text console and issue a startx, from whick I seem to get Gnome, but not Unity :-(
Does somebody know if my system is now hopelessly messed up ? I have a LOT of things which were installed on my system (64 GB on my / SSD, /home is elsewhere) ?
Also is there something somewhere explaining how to make Unity and KDE coexist on the system and be chosen at session start time, at least until I know them both enough to be able to make an enlightened choice ? I remember it was possible with some former versions of Ubuntu, though KDE did not seem easy enough to master at the time.
Any kdm, lightdm or gdm guru here ? (I tried to reconfigure them and choose one different each time, without any more success). By the way, I had an autologin previously and did not know how to remove it. Might that be part of the problem?
Thanks to whoever has or may have a clue. There is clearly something I am not grasping clearly :-/