As of Firefox v45 this addon is no longer working.
Now you can clear history before/after or between dates of your choice.
This extension adds additional options to the "Clear Recent History" window.
By default Firefox will clear ALL session history regardless what time frame was selected. As of v1.2 you have a choice weather you want clear session history or not.
(session history affect back/forward buttons in each tab)
In the App button (orange button) go to History -> Clear Recent History.
Or press CTRL + SHIFT + DELETE
Bug reports and/or suggestions, please submit at the support website: https://goo.gl/Pf85rY or via email posted at http://goo.gl/EPP0T