Rated 5 out of 5 stars

Tabs Always In Titlebar is one of those excellent add-ons that provides a feature that should be included by default.

Update: as indicated below, in version 1.0.1, extensions.tabsalwaysintitlebar.offset takes effect immediately. Thank you.

This review is for a previous version of the add-on (1.0). 

Thanks for the feedback. Please update to 1.0.1, the changes now apply instantly.

https://addons.mozilla.org/firefox/downloads/file/122519/tabs_always_in_titlebar-1.0.1-fx-windows.xpi?src=version-history