I was excited about the upgrade to the "activity chooser" in 2.3 to match the question creation process in the Question Bank that appeared in 2.0 or so. Unfortunately, it's not appearing correctly at all (similar to the problems I'm having with the File Picker: http://moodle.org/mod/forum/discuss.php?d=206763 )
I have attached a screenshot. Behaving like this in Chrome, FF, and IE. Caches cleared locally and on server...
Should look like this, FYI: http://docs.moodle.org/23/en/File:activity_chooser.png