No EXP bar on HUD

No EXP bar is present on my Ubuntu 13.04 machine when playing survival mode with the 13w16a snapshot. Launcher's not throwing any exceptions that I can see that would be related to the problem (only a rather trivial FileNotFoundException because a 1.6 data file isn't ready yet). Incidentally, an option to keep the launcher open would be lovely, as we can give you the stack traces for our builds). 🙂

It's also not showing any EXP orbs when mining or killing chickens, though the sound of the orbs being picked up is still playing for me.