Ubuntu :: Customize Keyboard Shortcuts For Few Accented Characters

In Welsh, we have a variety of accented characters - 56 with diacritic marks. Most are fairly rare, and accessing them via the Character Map is not really a problem, although it does slow down typing.There is a superb utility, provided free, which works on Windows systems only, and which maps the commonest accented characters.

I am recycling old PCs, installing Ubuntu, and distributing them in a predominantly Welsh-speaking area, and would love to be able to set up the same pattern of keyboard shortcuts for users.I have looked at using the COMPOSE key, but that means up to 6 keystrokes. I have also looked at keyboard preferences, bindings, custom layouts etc, but feel a little bit out of my depth. It doesn't appear as if there is a simple solution to this. A bit of time asking around and using search engines would appear to indicate that nobody has cracked this problem for Ubuntu.

Naerly all users will have UK keyboards, and being bilingual will be content with that.Is there a simple way of adding the extra characters, via the keystrokes described, for i386 systems running Ubuntu 10.04, system-wide, in all applications, for all users?