Comment 5 for bug 577933

I have some additional information. :-\ Did I mention that during the day I work as a professional SW tester? :D

As I mentioned, I use "Alt+Shift" (the MS-Windows like behaviour). Today I tried every possible combination of left-right side of keyboard and alt-shift. Whenever I use the right-Alt, with either left or right Shift, it works only once! That is: whatever order you have the layouts listed in Keyboard Preferences > Layout, you can only advance down that list, but cannot jump back to the top - which in all other cases you can. I don't know if this makes sense.
Bottom line is: I can prove that the right-Alt works, just not in one specific situation. Therefore I suspect this to be a software problem, and not a hardware problem.