1106280 - Vertical scroll position is not saved when pressing back button

Status: RESOLVED WORKSFORME

(Core :: Panning and Zooming, defect)

Description

[Kevin Grandon :kgrandon]

This is probably a dupe, but I can't immediately find the bug. One of my biggest painpoints when using the browser is that the vertical scroll position is not saved when pressing the back button.

Comment 1

[Kevin Grandon :kgrandon]

Smaug, Kats - By chance do you guys know how this works today on B2G? It seems when I press the back button the page instantly loads, so I assume we're leveraging some kind of cache here. The scroll position is unfortunately not remembered though. Any pointers/ideas?

Comment 2

[[:fabrice] Fabrice Desré]

Strangely, this sometimes work, sometimes not, even on the same site.
Though I think that never works in reddit.com if you need a testcase.

Comment 3

[Olli Pettay [:smaug][[e-mail]]]

Do we do the panning/scrolling asynchronously on b2g? If so, could this be a timing issue?
And indeed, position is saved occasionally. A testcase showing when the position is saved and when
not would be good.

Comment 4

[[:fabrice] Fabrice Desré]

Yes, we're doing async pan/zoom on b2g, except in the system app but that doesn't apply there.

Comment 5

[Kartikaya Gupta (email:[e-mail])]

In general restoring the scroll position should work, since that happens in the layout code and then pushed over to the APZ/compositor via the usual mechanisms. From prior experience on fennec though there might be cases involving things like pinch-zoom or font inflation which affect the scroll position or where content visually appears on the screen and layout's restored scroll position might not take those into account. :esawin landed some code not to long ago to fix some of these cases on fennec and we might need to use that code on B2G as well. If we have reliable STR then we should be able to investigate and fix it.

Comment 6

[Kartikaya Gupta (email:[e-mail])]

(Feel free to request blocking status if you feel this is important and we can prioritize accordingly)

Comment 7

[[:fabrice] Fabrice Desré]

Kats, you can repro 100% by loading http://reddit.com/.compact, scrolling down open a page and then go back in history.

Comment 8

[Gregor Wagner [:gwagner]]

Is this still happening?

Comment 9

[Kevin Grandon :kgrandon]

(In reply to Gregor Wagner [:gwagner] from comment #8)
> Is this still happening?

Yes, but not on all sites. Reddit.com is a good example.

Comment 10

[Gregor Wagner [:gwagner]]

Adding Milan for prioritization.

Comment 11

[Milan Sreckovic [:milan] (needinfo for best results)]

We can add it to backlog.

Comment 12

[Olli Pettay [:smaug][[e-mail]]]

Kevin, has the situation perhaps improved a bit (in Nightlies)? There was a change to scrolling / popstate handling which made us work closer to webkit/blink.

Comment 13

[Kevin Grandon :kgrandon]

After playing with scrolling for a bit, this actually seems much better now. I'll file a new bug if I see anything, thanks for the work here!

Comment 14

[Olli Pettay [:smaug][[e-mail]]]

The change happened in Bug 1186774.