Still keyboard trouble

Hello all, I allready mentionned this problem, but it seems to get worse recently: I use Keyboard Layouts (enabled through Trinity Control Center). I set "German (Switzerland) ch, fr variant, as first Layout, with English (US) as second option. This works fine, except that I often loose the function of the "Alt Gr" key (for those who only know the US keyboard, Alt Gr is necessary to access a bunch of characters we use in non-English languages. This in inconvenient as it means I loose {} and [], but as I don-t program a lot... However we need the Alt Gr key also to get @, and it so happens that I use it in passwords that usually have to be typed in blind. I know where to find it on the US keyboard, but I have no way to know if my Alt Gr works or not before a password fails. This is independent from distribution (I had hoped that switching to Jessie and 14.0.2 would help, but not). What I don't know is what is causing the problem. The rest of the keyboard layout continues to work, only Alt Gr is gone. So far only loging out and in cures the problem. Anyone has a clue to what causes this? Thierry