Right-Alt not working? A possible fix

[Patrick Wiseman <pwiseman@gmail.com>]

Hello:

After a recent testing upgrade (I do it daily, but this happened two
days ago), my right-Alt key was not working properly.  Eg, in
Iceweasel, Alt-left should go to the previous page.  With the right
Alt key, nothing happened; with the left Alt key, it behaved as
expected.  Googling revealed that, in Ubuntu, the right alt key
"chooses 3rd level", but that did not seem to be so here when I
checked System/Preferences/Keyboard.  But selecting the option "Right
Alt key never chooses 3rd level" under the "Key to choose 3rd level"
option appears to have corrected the problem.

I never had this problem before; is Debian making some eurocentric
presumptions (use of 3rd level on the keyboard) in its defaults?  I
have no objection to that, except that when I select a US keyboard I
would not expect those presumptions to operate!

Patrick