User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:26.0) Gecko/20100101 Firefox/26.0 (Beta/Release) Build ID: 20131215161728 Steps to reproduce: 1. Have one Firefox window with two or more tabs. Open any sidebar (menu View > Sidebar) in the first tab. Demo path I: 2. Switch to the second tab within the same window. The same sidebar shows up there. 3. Open/activate a different sidebar (menu View > Sidebar). 4. Switch the the previous tab. The sidebar there got changed, too. That's not very user friendly. Demo path II: (continuing after the previous steps): 5. Close the sidebar on the current (first) tab using its 'X' corner icon. 6. Switch to the second tab. The sidebar got closed there, too. This is not user friendly. Actual results: as above Expected results: Allow sidebar to be selected and turned on/off independently/separately for each tab in the same window. Probably worth implementing together with https://bugzilla.mozilla.org/show_bug.cgi?id=932578.