I don't think there is any app to make custom keyboard settings in Lunux. I would be a great idea to make one.
The link you copied in your Dec 05 post details the method I use. I edit the us keyboard to add additional letters (ÁÉÍÓÚáéíóú€≠±£ in my case) and once I set it up the way I wanted I kept a backup on dropbox so I can reinstall it easily if necessary. I also set they key to get the third level (keyboard layout ->Layouts->Options->Key to choose Third Level) Make sure this is set to what yo expect.
I know how to make custom keyboard maps, but I don't think it is easy so I am not very confident in explaining how to do it. Perhaps you can tell us how far you got following the advise given in this link? Were you able to change any key?http://www.dotkam.com/2007/06/25/custom-keyboard-layout-in-ubuntu-or-just-linux-2/
Sorry for replying so late, but I never got the notification of your comment! I actually was coming here for bumping this, didn't expect to find your reply, it was quite a surprise. I left Linux Mint for a long pause with Windows 8 (and I actually find it Okay usability-wise) but as it was the Consumer Preview it got deactivated at the end of 2012, so I had to regress to Windows 7. I just recently reinstalled Mint, at the end of May - when Qiana came out.
I tried to research since last week, and I am amazed that still in 2014 nobody ever thinks that it would be handy. I tried to ask in google+ (https://plus.google.com/109134171685799811475/posts/TZZ3H8ypLZ5
) as well, and as usual there are the Linux fanbois who don't explain nothing, bash Windows without knowing and give wrong suggestions: at the question how to remap the keyboard, the answer was to use compose, which isn't exactly the same thing. It's just using a preset keyboard layout which doesn't work for me.
Anyway, I tried this afternoon modifying my usr/share/X11/xkb/symbols/it file as explained in the dotkam blog, first pasting the letters I wanted because I thought the system could recognise them, but got an error of configuration, so I looked up how to give the various letters a proper name, and once everyting was at it should have been, still it didn't like it.http://i299.photobucket.com/albums/mm315/look-aa/Screenshotfrom2014-09-17161702_zpsff9f0376.png
Maybe it has to do with the fact that I added more keys to the list, I don't know where xkb is taking the other letters from, maybe I shall modify another file?
I'm trying since 2 pm and now it's 5:30 and I am still stuck. Honestly, that's why people who don't know about computers hate Linux - I totally understand them.
I really don't know if it's worth doing what I am attempting to do since 2 years ago, and when I look at the date when that dotkam post was written... 7 years ago! No progress whatsoever, almost 2015 and still compiling to modify a keyboard, when with Microsoft anybody can do it conveniently with their mouse since Windows XP SP1 times, or probably since Windows 98.