1357061 - 0.98ms uninterruptible reflow caused by underflow event at get_scrollClientRect@chrome://global/content/bindings/scrollbox.xml:131:18

Status: RESOLVED FIXED

(Firefox :: Tabbed Browser, defect, P1)

Description

[Florian Quèze [:florian]]

Here's the stack:

get_scrollClientRect@chrome://global/content/bindings/scrollbox.xml:131:18
ensureElementIsVisible@chrome://global/content/bindings/scrollbox.xml:241:15
onxblunderflow@chrome://global/content/bindings/scrollbox.xml:765:13


This happens when increasing the width of a browser window. I don't understand how this action could cause the current tab to become invisible, because if there's no overflow anymore, all tabs are visible, right?

The relevant code is at http://searchfox.org/mozilla-central/rev/a7334b2896ed720fba25800e11e24952e6037d77/toolkit/content/widgets/scrollbox.xml#762

Comment 1

[Florian Quèze [:florian]]

Can we just remove these lines? http://searchfox.org/mozilla-central/rev/a7334b2896ed720fba25800e11e24952e6037d77/toolkit/content/widgets/scrollbox.xml#762-764

Comment 2

[Dão Gottwald [:dao]]

Not sure. This could be a workaround for weird layout behavior like http://searchfox.org/mozilla-central/rev/214345204f1e7d97abb571b7992b6deedb5ff98f/browser/base/content/tabbrowser.xml#5945-5953

Comment 3

[Florian Quèze [:florian]]

So should we just try and ask QA to verify with some exploratory testing? Or is bug 1356705 going to fix this?

Comment 4

[Dão Gottwald [:dao]]

(In reply to Florian Quèze [:florian] [:flo] from comment #3)
> So should we just try and ask QA to verify with some exploratory testing?

Fine by me.

> Or is bug 1356705 going to fix this?

Given the current WIP patch, it would remove the layout flush, but leave behind this potentially useless code.

Comment 5

[Florian Quèze [:florian]]

Attachment: Patch

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/3e59d06de614
remove potentially useless ensureElementIsVisible call (that currently causes a sync reflow) when an arrowscrollbox handles an underflow event, r=dao.

Comment 7

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/3e59d06de614

Comment 8

[Florian Quèze [:florian]]

We requested QA here because we don't really know what the lines we removed here were doing. It's code related to one (or more?) tab(s) making us leave the overflow mode on the tab bar.

Comment 9

[Adrian Florinescu [:aflorinescu]]

Removing the qe+ flag from this issue since the change is from 55 iteration + the areas that might've presented regressions have been already covered in different bug verification or exploratory/regression testing.