Created attachment 8648312 [details] Screenshot.2015-08-15.010650.png User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:42.0) Gecko/20100101 Firefox/42.0 Build ID: 20150814004009 Steps to reproduce: Launch Firefox Actual results: No tabs loaded (filed thay via the e10s ‘give us feedback’ question), and the browser presented an alert toolbar with white text on a light grey background saying: You’re now helping to test multi-process in Firefox Developer Edition! Please report problems you find. Expected results: The toolbar should have been themed correctly.
It looks like a theme issue. Are you running gtk3?
(In reply to Loic from comment #1) > Are you running gtk3? It appears this build is running with libgtk3, yeah.
Hey Andrew, know what's happening here?
Yup, seems to be a duplicate of bug 1187203, caused by some themes having a background-image set for tooltips but no background-colour.