User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:55.0) Gecko/20100101 Firefox/55.0 Build ID: 20170816204344 Steps to reproduce: I use a hundred of "common" tabs and a few pinned tabs. All new "common" tabs are opened on the right, so as the time goes, the less used tabs slowly disappear on the left. Pinned tabs are placed on the left, taken out of other tabs context... Actual results: ... When a new ("common") tab is opened from the pinned tab (very often), it is placed in front of the other "common" tabs and all the active "common" tabs are scrolled away and the less used ones appear. Then it is necessary to scroll all the tabs back (tens of seconds). Expected results: Pinned tabs are taken out of other tabs context, they are not just moved to the beginning, so the newly opened tabs should be also opened in a way which reflects that. Solution might be to create a new about:config option next to browser.tabs.insertRelatedAfterCurrent just for pinned tabs – users could set there the tabs opened from pinned tabs to be opened on the right. Alternatively, move pinned tabs to the right. Pinned tabs works similarly to system trays and on the most OSes, the systrays are on the right. Tabs opened from pinned tabs could be opened then just in front of them on the right of the other "common" tabs naturally.

This is working as expected, although we've occasionally talked about maybe revisiting that. No plans to do so right now that I'm aware of, though.

Opening the tabs on the right is really expected. The problem is the new tabs are opened on the right and the tabs opened from the pinned tabs are opened on the left. Both are opened simultaneously all the time, so all (hundreds) inactive tabs in between have to be scrolled all the time. This is IMO not intended. Anyway, many thanks for the reply. I am voting for a revisiting. ;-) (Just during this short reply I had to scroll back and forth seven times – my email client is pinned to be always available, so Bugzilla was opened furthermost to the left from there and all dictionaries and such things I needed to compose this message were opened furthermost to the right via Ctrl+N. Fortunately the original tab was usually restored after Ctrl+W.)