There is no support for fcitx in GNOME, at all, and we don't plan on having any support for it. Any support for fcitx in Ubuntu's version of GNOME is done by Ubuntu, not by GNOME.

I didn't file a report here because I thought you should have support for it, I just gave examples of what the options were on my machine to give a general sense of what was there.

Even if you don't support fcitx, are you still not able to provide an option which allows you to switch between "none" and "IBus"? Because I need "IBus" and as the default seems to be "none" I have to install gnome-language-selector to configure it.

The methods are dependent on your "input sources" choices. If an input source needs ibus or raw X11 doesn't matter to the user, and will be handled transparently. There's nothing for the user to select.

Really? Because I've been trying to get Japanese working as one of my input sources and the only way seems to be to install gnome-language-selector and change it from "none" to "IBus"...

That's not necessary in GNOME. For example, trying to type Rおまじ (Romaji) with the kana kanji input method. I didn't need to select the ibus input method, because gnome-session already sets that up:
gnome-session/main.c:                        gsm_util_setenv ("QT_IM_MODULE", "ibus");
gnome-session/main.c:                        gsm_util_setenv ("XMODIFIERS", "@im=ibus");

I'm guessing that the Ubuntu GNOME version breaks that though.

Well, that doesn't work for me, so what should be done about this?

Tell your distribution, I'm certain it works correctly on Fedora and Debian so the problem is an Ubuntu specific problem.

You mean I should just report the issue on LaunchPad? And if so, under which package?

Ah, sorry, I slightly misread one of your previous messages which led to my confusion... So should I file a report under gnome-session on LaunchPad?

fwiw Ubuntu GNOME does not even ship with fcitx.

Well, all I know is that it's an option in the gnome-language-selector... Though I've never actually seen it there before... I don't think it was there when I was running Ubuntu GNOME 15.04 with GNOME 3.16.

we don't ship gnome-language-selector either that is an Ubuntu (Unity) thing

I know, I installed it because the built-in version doesn't seem to install all the correct language packs... I just thought that if there is an option the gnome-language-selector which fixes the issues I am having, then the option should also be in the built-in version... Though it seems that there are just some problems with the Ubuntu GNOME version of gnome-session or something...

Strange... I thought I got it working by setting the setting in the gnome-language-selector to "IBus", but it still doesn't actually seem to be working... It still just gives me English... So is this a bug in gnome-session or...? I mean, the reason I'm asking here is because I'm not sure where to file a report on this, nor where would be a better place to ask...

gnome-language-selector isn't an upstream project, it's an Ubuntu specific package:
https://launchpad.net/ubuntu/+source/language-selector

Ask Ubuntu and/or Ubuntu GNOME about your problem.

I think he was saying that he installed gnome-language-selector, since it wasnt working. afaik we don't have any patches that affect input methods/ibus, atleast not in the GNOME parts, Ive never really looked at the lower level parts though like ibus itself. I will check with Gunnar though, he might know.

Yeah, I initially just installed "Japanese" through the standard way in the gnome-control-center, however when that didn't work and I only got English when typing using the "Japanese" input source mode, I install the gnome-language-selector to see if that would fix anything, and it didn't... So I think we can forget about the gnome-language-selector as the standard way also didn't work, so it's probably something more internal because all the external tools aren't working...

Ah, wait, no I think I set Japanese as an input source, but when that did nothing I installed the language packs through the gnome-language-selector... If that helps at all... I don't know, I might try uninstalling it and the gnome-language-selector and then trying to install it the standard way to see if it makes any difference (though the standard way seems to miss out some language packs, but I'll obviously file a report on that separately)...

I found the issue with the Japanese typing by the way... It seems that for some reason 'language-selector-gnome' was conflicting with something else on the system and therefore 'Japanese (Anthy)' was not showing as a possible input source, however after purging the 'language-selector-gnome' and rebooting I found that I was able to add 'Japanese (Anthy)' as an input source so I can now type in Japanese.