The nav bar's mockups by Stephen Horlander show a inactive state for buttons. It allows users to spot more easily if the window is focused or not. It's a nice to have.
Are you sure this isn't just the button disabled state ?
On this old mockup it's clearly written "inactive" and not "disabled". Maybe UX input would be good then.
(In reply to Tim Nguyen [:ntim] from comment #1) > Are you sure this isn't just the button disabled state ? Sorry, yeah I guess I should clarify that it means disabled button state. Thanks!