Dev Build 2131
is out now. The major change is that side bar animations are back, and they're working in a more usual way.
I've added a global setting to disable all UI animations ("animation_enabled"), but it's currently a hidden setting not listed in the defaults, as it really does disable all animation, which I suspect is not quite what everyone wants (e.g., animation on new tabs is disabled, as is animation when dragging tabs around).
For those who aren't keen on the UI animation in general, I'd like to hear if you only want to disable the side bar expand/collapse animation, or all animations.