not so much a bug, but a thing to know. 2.53

just an thing to note. if you load a 2.4x file in 2.5. change some stuff… etc. save user defaults. you lose the operators panel and won’t get it back without resetting user defaults. (as far as i can tell)

it happened when i opened my 2.49 b.blend and changed some settings ( addon options) and set as my default. quick skip to transfer my old preferences, didn’t work so well…

And if you uncheck Load UI?