User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:35.0) Gecko/20100101 Firefox/35.0 Build ID: 20140924030204 Steps to reproduce: Go to a web site with some certificate problems (e.g., https://www.amnesty.org.hk/ ) Actual results: A “This Connection is Untrusted” screen appears with an “Add Exception” button. Pressing “Add Exception” brings up yet another dialog, with an “Add Security Exception” button. Pressing “Add Security Exception” produces no effects. Expected results: Pressing “Add Security Exception” should allow the visitor to ignore the security warning (which is indeed what happens if the window is non-e10s)