keyboard gets weird after pressing tab, arrows and some other keys

[fhars]

If you start http://0x10co.de/htg6u it will echo every (ascii) key on the screen, and return does work, too, but if you hit tab, the program will not see it (and switch to the next screen) and instead further keyboard input will be bunched and out of order. All dead keys, arrow keys, PgUp/PgDown and Fn keys have the same effect.
I'd like to tell you which version of firefox I'm running in case the behaviour is browser dependent, but all I can say is that it is one affected by this: https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/920606