The UI is not broken, but it feels bad. The UI updates twice per second, and when I hover over a button, it shortly flashes twice per second (the button's default color shortly flashes over the button's hover-color). Worse, when I'm switching tabs, the actual menu change also only happens on the twice-per-second-cycle. I think some clicks also aren't registered correctly, probably the ones happening exactly during a UI flash.
This results in a bad looking and sluggish feeling UI.