The lack of clear affordances in the Microsoft design really bothers me.
* When two buttons are next to each other, do they behave as tabs, toggles or buttons with disparate behaviors? You can't tell.
* is an icon next to a field actionable? I have no idea until I try to click it.
* These buttons are very reliant on :hover to indicate behavior. That's not very useful for users on touch devices (Is the button intentionally disabled, or is it broken?)