On Ubuntu 12.04, I added 4 keyboard layouts using the + button. Since then, the + button has been disabled and I cannot add more layouts.
Is there a limit to the number of keyboard layouts?
I just did a clean install of 15.04 (the upgrade attempt from 14.10 was a disaster) and I cannot figure out how to add my keyboard layouts for various languages. I saw something about a tab for layouts in System Settings -> keyboard, but I have no layouts tab. Is there a package I have to install?