It is easy to add and change languages in Ubuntu with the default Unity desktop environment.
You just have to to Languages & Support -> Install / Remove Languages... and add which ever you want.
How can I do the same in Ubuntu GNOME 16.04?
Adding Input Sources without adding corresponding language results in unsupported characters :
Actually, Region & Language in Ubuntu GNOME does basically the same as Language Support (language-selector-gnome) when it comes to adding languages, even if the UIs differ. However, you are right about Kannada - for some (to me unknown) reason it's available as a language in Language Support, but not in Region & Language.
When you add a language, some language support is installed besides the translations, including extra fonts if applicable. So it's advisable to install the language first if you are about to add an input source for some non-latin script. This is true for both Ubuntu GNOME and other flavors.
With that said, and even if Language Support is not installed by default in Ubuntu GNOME, it's compatible with Ubuntu GNOME, and can be useful as a supplement occationally.
It is inadvisable on GNOME to install the language-selector-gnome as it is a Unity tool and manages to interfere with the pre-installed system for dealing with language packs and input sources (especially with the IBus).
The built-in method to install additional language packs (and you have to install the language pack before you can add the input source) is as follows:
Region & Language section of the gnome-control-center:
Language in order to get the language selection up:
In the search box at the bottom search for the language you want to install.
Select the language(s) you wish to install (a tick will appear next to the selected languages) and then click Done.
After doing so a box similar to do this one will appear, check that you are happy with what will be installed and then click Install, you will be prompted for authentication and may get another installation box on which you should also click Install if you get it:
Note: If there is a language that you find can only be installed properly for some reason through the language-selector-gnome install it through there but after doing so purge the language-selector-gnome, then you will get the language pack you want, but the program won't interfere with your system.
language-selector-gnome interferes with system for language packs and input sources in Ubuntu GNOME, needs to be backed up. There indeed was a reason for confusion for a short period, but it has been fixed in 16.04. It's simply not true, AFAIK, that the pure presence of language-selector-gnome makes a difference. So Paranoid Panda, if you can show such an example (in 16.04), I'd appreciate if you could give me the details, because then it's a bug which should be fixed.
May 26, 2016 at 19:32
im-config, not language-selector-gnome. (And it shouldn't prevent you from installing Anthy. I tested it intensively when working with that bug.)
May 26, 2016 at 20:00
Since the idea with Ubuntu GNOME is to provide GNOME software, the default tool is Region & Language.
To get Language support, the package language-selector-gnome has to be installed.
So install language-selector-gnome to add and change languages in the way you used to do.
Execute : sudo apt install language-selector-gnome.
Now any language can be added and configured as usual.
language-selector-gnome is not accidentally "missing". It's not present by default since the idea with Ubuntu GNOME is to provide GNOME software, and the corresponding GNOME tool is Region & Language.
May 26, 2016 at 15:37
language-selector-gnome package on GNOME, that would be rather advised as it does cause some problems with the IBus and is not needed to install additional language packs.
Language English (United States)line, what happens?Language English (United States)will be overwritten . Can't have both simultaneously :-(