I can reproduce the problem in Developer Edition, but in Nightly it works fine. Shaun: do you have the chance to test in Firefox Nightly and see if you can reproduce the problem there?
Bug 1572933 Comment 2 Edit History
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I can reproduce the problem in Developer Edition, but in Nightly it works fine. Shaun: do you have the chance to test in Firefox Nightly and see if you can reproduce the problem there? Also, do you have any extensions installed?