I just found this bug when I clicked on the StackExchange button and other buttons. Some orange-dotted lines appear around the button when I click on it.
Since no one posted an answer on this so it can get closed I'm now putting my comments into an answer:
Well its something your browser does, not the site itself, thats inevitable, and not a bug.
Reporting things is still fine and encouraged, but please remind if it is a serious bug or security risk it would be better to mail it directly to the SE team instead of posting it here.