Thread:Extension talk:AddThis/Incompatibilities between AddThis and HeaderTabs/reply

I can confirm this one. I have tried just about everything - showing addthis in sidebar, header or elsewhere on the page and it doesn't matter. The moment it is displayed it breaks headertabs.

I tested a bit further by using the Widget extension to create my own addthis and that breaks too. In other words - the problem is with the javascript of the addthis button.

Final test was trying the addtoany site instead of addthis, and that one works. Guess I'll be using a widget for now :)