1541400 - Pinned tabs are moved out of view, when the tab overflow scroll buttons disappear

Status: VERIFIED FIXED

(Firefox :: Tabbed Browser, defect, P1)

Description

[Gyula Palko[:gpalko]]

Affected versions:
Nightly 68.0a1 (2019-04-02) (64-bit)

Affected platform:
Windows 7/10
Ubuntu 16.04
Mac OS 10.13

Steps to reproduce:

• Launch Firefox Nightly
• Open and Pin a few tabs
• Open new tabs, until the tab overflow scroll buttons(< >) appear(~15-20 tabs)
• Click the < button, until it becomes inactive(you reach the first tab)
• Close some tabs, until the overflow buttons are not visible anymore

Expected result:
All tabs are visible, pinned tabs section is not affected

Actual Results:
Pinned tabs are moved out of view, to left, when the < > tab overflow buttons disappear.

Note
On MacOS, a vertical bar is visible on the first pinned tab's favicon, and there's an extra space after the pinned tabs section

Regression-range: will try to find it asap.

Comment 1

[Alice0775 White]

Regression window:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=ccfd61724e92f10efc8a7a45af44b1ee0c992cf8&tochange=66fa0672d6ea057164bcd9aebfe7323c162b1a30

Regressed by:
66fa0672d6ea Brian Grinstead — Bug 1539665 - Handle the tabbrowser-arrowscrollbox XBL logic from within tabbrowser-tabs r=dao

Comment 3

[Dão Gottwald [:dao]]

Screen recording from duplicate bug 1541403: https://youtu.be/kH3_19YTKhY

Comment 5

[Brian Grinstead [:bgrins]]

I see this error in the browser console when reproducing:

TypeError: this._scrollButtonDown is undefined tabbrowser.xml:157:15
_initializeArrowScrollbox chrome://browser/content/tabbrowser.xml:157

Comment 6

[Brian Grinstead [:bgrins]]

Attachment: Bug 1541400 - Reference the scrollButtonDown field from the arrowscrollbox and not tabbrowser-tabs;r=dao

When this handler got changed to an arrow function the reference didn't get
moved onto the scrollbox.

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/e3b36e27cd60
Reference the scrollButtonDown field from the arrowscrollbox and not tabbrowser-tabs;r=dao

Comment 8

[Cristina Coroiu [:ccoroiu]]

https://hg.mozilla.org/mozilla-central/rev/e3b36e27cd60

Comment 9

[Dan Ceban [:okazki98]]

Retested on build: 20190405095028. Works as expected for me now.

Comment 10

[Brian Grinstead [:bgrins]]

(In reply to Dan Ceban [:okazki98] from comment #9)

Retested on build: 20190405095028. Works as expected for me now.

Thanks for checking - marking as verified.

Comment 11

[Cristian Comorasu, QA [:ccomorasu], Releae Desktop QA - Please contact [e-mail]]

Based on comment 9, I am updating the tracking flag.
Thank you!