1327957 - Tabs strip scrolls towards the end when I restore tab

Status: NEW

(Firefox :: Session Restore, defect)

Description

[arni2033]

>>>   My Info:   Win7_64, Nightly 49, 32bit, ID 20160526082509
STR_1:
1. Open new Firefox window. Open many tabs to cause overflow in tabs toolbar. Open 5 more tabs
2. Scroll tabs strip to the start
3. Select the 3rd tab, navigate to  http://example.org/  in that tab
4. Close the tab (Ctrl+W). Restore the tab (Ctrl+Shift+T)

AR:  Step 4 - all tabs teleport to the left by ~15px (i.e. tabs strip scrolls to the right)
ER:  No movement in tabs toolbar

Comment 1

[Stefan [:StefanG_QA]]

Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:53.0) Gecko/20100101 Firefox/53.0

I have tested your issue on latest FF release (50.1.0), latest Nightly build (20170103030204) and managed to reproduce it. I have noticed that the tabs are moved to the left as reported. 

I will use mozregression tool in order to find a regression window.

Comment 2

[Stefan [:StefanG_QA]]

Mozregression wasn't very useful here. 
I've needed manually to narrow down the regression range. 

Here are my findings: 

Last good release version: Firefox 3.6.28
First bad release version: Firefox 4.0

Comment 3

[BugBot [:suhaib / :marco/ :calixte]]

The severity field for this bug is relatively low, S3. However, the bug has 21 votes.
:dao, could you consider increasing the bug severity?

For more information, please visit auto_nag documentation.

Comment 4

[BugBot (nomail) [:suhaib / :marco/ :calixte]]

The last needinfo from me was triggered in error by recent activity on the bug. I'm clearing the needinfo since this is a very old bug and I don't know if it's still relevant.