Rated 4 out of 5 stars

yazan: fremea tarih: Haz. 26, 2015 · kalıcı bağlantı

Tested on a fresh profile:

About the fact that it brakes the possibility to customize your navbar, it's true and it's not a conflict with another add-on. It happens if after having customized your navbar, you use a restart command from the addon manager (or another add-on or userscript button). Then when firefox reopens, it's forgotten what you've just done.

So, when you have made some customization, just remember to close firefox with the quit button then.
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The author should investigate why it happens when his add-on is enabled. I have about 100 other add-ons and none has this issue.