Since a few days, I've noted that alt+shift+p on edit does nothing in master with Firefox (monobook). I'm at 17.0.1 and I don't remember updating it in this timeframe (I think I would have noticed but I'm not 100 % sure).
I've just verified that it's the same in 1.21wmf6 and with Vector, while alt+p seems to work on Chromium.
In my tests a moment ago, on some occasions alt+shift+v (show changes) didn't work either, or (in Vector) it selected the button without activating it (!), but I'm unable to reproduce right now.
If this is actually a problem on MediaWiki's end, it's quite a big regression.
Version: 1.21.x
Severity: normal
OS: Linux
Platform: PC