I've discovered a really annoying but apparently intentional behavior in Mac OS X where if you open a menu in the typical click-and-release fashion, if the menu takes too long to appear (e.g. if it has to do some computing), the menu will immediately close again as soon as it appears.
It's incredibly frustrating. I can only imagine it has something to do with supporting the archaic click-and-hold menus that the original Mac OS had.
Does anyone know how to disable this timeout so the menu won't close as soon as it appears?