@Suiseiseki

> some keyboards have multiple keys wired up to the same wire and therefore certain key combinations go unrecognized

Interesting idea. As I mentioned in my previous post a friend gave me her laptop for testing. It's weird that in her keyboard, with qwerty layout, C-a, C-t are not recognized at all, even though they are recognized when pressed individually, or C-v, C-c are recognized fine. One would assume C-a and C-t are not that uncommon combinations so they should be recognized.

Another thing is, I was playing super tux kart on it, and again when I pressed <space bar> when up arrow was already pressed, space was going unrecognized.

My first impression was maybe I configured keyboard wrong when I installed GNU/Linux, but then why would those keys work fine when pressed individually? Now that you mentioned this point I'll keep that in mind when I do further testing later. And if it's really as that you mention, I will tell her to replace that garbage keyboard.