Seems like the correct issue/bug for OP is actually this: IDEA-78860
This is not a Ubuntu version specific, but X Window / IBus problem and it is still happening in Ubuntu 14.04 with IBus < 1.5.11
Update IBus to 1.5.11 or higher
Check this answer on how to update ibus on ubuntu
Official workaround, is to add following line to your ~/.profile
Remember you have to restart your session (logout) for this to take effect.
The most universal workaround is still
ibus restart, but I think it is worth to quote the assignee of the issue:
Restarting IBus isn't recommended (may crash the IDE later)
Yes, that may happen sooner or later. Also this resets your keyboard layout to default (mostly english). So you'd have change that back every time you restart ibus.
Another option is to disable ibus, but this really is not a solution for people who do not have US kb layout.