After achieving level 50, one will occasionally receive the skill advance screen (based on # of skill checks and xp?). However, the screen is thrown up with no warning and without even waiting for the cause to show.
To replicate:
Save game: http://ancardia.us.to/tmp/PostFift.svg.gz (1.2.0p4 Debian 32-bit save) (gzip'd)
Use Disarm Traps on the door and fail (but don't set it off either). The skill up screen pops up and "You do not manage to disarm the trap." appears only in the :m log. Also, there's no record of the skillup in the message log.
Desired behavior: "You do not manage to disarm the trap. Congratulations! You advance in your skills. (more)" or similar verbage and THEN the skillup screen appears.
I got a skill advancement while flinging arrows in D:49. Definitely no one else on the level except me. What triggers post-level-50 skill advancements, if not experience points?