I don't know what's going on, exactly -- and I'm kind-of annoyed that your buttons don't show up in "Customize" ... but I'm using the new TabCenter extension from the Firefox Test Pilot and the result is that the only button that shows up in the diigo toolbar is the "Go premium!" button.
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https://github.com/bwinton/TabCenter
https://testpilot.firefox.com/experiments/tab-center
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