On my OSX box (mbp) the context menus and popups are horridly misplaced and popup in random locations on the screen. For the popups the pointer is also often completely misaligned with the menu items requiring item selection to be clicked dozens of pixels away. I've also long given up throwing TB to a different display - text, UI sizing and menus explode and it becomes unusable on any other monitor.

Having said that it's still the best email client software I can find - UI issues aside.