scroll tab-bar using < > arrows jerks & is slow




Tabbed Browser
7 months ago
6 months ago


(Reporter: Bill his name, Unassigned)


57 Branch

Firefox Tracking Flags

(Not tracked)




7 months ago
User Agent: Mozilla/5.0 (Windows NT 10.0; rv:57.0) Gecko/20100101 Firefox/57.0
Build ID: 20170805100334

Steps to reproduce:

using Nightly 57.0a1 (2017-08-05) (32-bit) under windows10

Get several tabs (more than tab-bar horizontal allocation).

Use < > arrows at sides of tab list to scroll tabs (left or right)

Actual results:

Slowly, slowly, & jerkily
the tab-bar moves in tab-sized increments.
I  estimate  the  rate  to  be  700ms  per  tab

This.  languid.  sluggishness.  interrupts.  work flow.

Using mouse-wheel to scroll tabs remains acceptable smooth scroll. 

Additionally, when horizontal scrolling inside a rendered page using keyboard arrows,
there is similar slow jerky behaviour.
Is this related?

UX - Also, it is difficult to regain focus to current tab if tab is scrolled out of view.

Expected results:

When using < > arrows, tabs should scroll nicely at a usable rate.

Not too slow, not too fast, just right for everybody. Regardless of reaction times or impatience quotient.

Whether smooth or in tab-sized increments is a matter of personal preference for Users. 
IMO, the jerks do have potential for increasing precision.

{Where can one see, discuss & actually influence style points?}

.. Similarly, so should web-pages scroll politely when using keyboard arrows. 
No jerks. 

Adjunct: it should be easy to regain focus on current tab when it has moved.
Because one may need tab drop-down buttons.


7 months ago
Duplicate of this bug: 1387760

Comment 2

7 months ago
Additional to above, I notice intermittent behaviours.
Sometimes if I hold the "<", the tabs will move, but when I release the "<", they jump a further few places.
This is very unappealing.

Comment 3

7 months ago
Possibly related difficulty regaining focus on current tab:


7 months ago
Component: Untriaged → Tabbed Browser

Comment 4

7 months ago
Probably a dupe of bug 1387084? Is this better in more recent nightlies?
Blocks: 1387084
Flags: needinfo?(billachenal)

Comment 5

7 months ago
57.0a1 (2017-08-06) (32-bit) continues the behaviour.

Playing around, I did note that using < or > can cause quite erratic jumps, worse under conditions of load = many browser windows & many tabs (+ maybe youtubes as well). 
Running under win10, on an oldish laptop dell Latitude D520 (adequate, 4GB, Core2 CPU T5600 @ 1.83GHz
Works ok if I am cautious & caeful). I suspect less of a problem for more capable rigs.

+ I think there was a config item at one time to smooth-scroll tab-bar (which still happens if I use mousewheel); I wonder if that is/was relevant.
Flags: needinfo?(billachenal)

Comment 6

7 months ago
There's a regression range in bug 1388070, so duping there.
Last Resolved: 7 months ago
Resolution: --- → DUPLICATE
Duplicate of bug: 1388070

Comment 7

7 months ago
Moved relevant comments (comment 5 & above)to bug 1388070, so no need to revisit here.

Comment 8

7 months ago
... which was again marked dup of 1387130, so moved comments there too. Perhaps it will rest there.
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