Markus Stange [:mstange] Assignee
	Description • 8 years ago

STR:
 0. Use overlay scrollbars on OS X.
 1. Go to http://steamcommunity.com/app/255710/discussions/0/451850849200785255/
 2. Press space to scroll down by one page.
 3. Press shift+space to scroll back up.

Now the header will briefly have white parts on the left and the right side. These parts get redrawn with the correct dark blue color once we trigger a paint when the scrollbars fade away.

While the white is visible, you can also see remnant scrollbar pieces, indicating that we're not compositing anything to that part of the window. Usually this happens if we have an opaque ContainerLayer with contents that don't cover the complete visible region of that ContainerLayer.

	Markus Stange [:mstange] Assignee
	Comment 1 • 8 years ago

Apparently the window width needs to be <= 1438px for this to happen (the width of the fixed background image).

	Markus Stange [:mstange] Assignee
	Comment 2 • 8 years ago

This is caused by hideAll being set to true in PostprocessRetainedLayers even if the opaque layer has a scrolled clip.
I have a fix.

	Markus Stange [:mstange] Assignee
	Comment 3 • 8 years ago

Review commit: https://reviewboard.mozilla.org/r/69452/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/69452/

	Matt Woodrow (:mattwoodrow)
	Comment 4 • 8 years ago

Comment on attachment 8778039 [details]
Bug 1259872 - Don't cull all layers under an opaque layer that covers the container if that layer has a scrolled clip.

https://reviewboard.mozilla.org/r/69452/#review66576

	Pulsebot
	Comment 5 • 8 years ago

Pushed by mstange@themasta.com:
https://hg.mozilla.org/integration/autoland/rev/a008184ea135
Don't cull all layers under an opaque layer that covers the container if that layer has a scrolled clip. r=mattwoodrow

	Phil Ringnalda (:philor)
	Comment 6 • 8 years ago
bugherder

https://hg.mozilla.org/mozilla-central/rev/a008184ea135

	Markus Stange [:mstange] Assignee
	Comment 7 • 8 years ago

Comment on attachment 8778039 [details]
Bug 1259872 - Don't cull all layers under an opaque layer that covers the container if that layer has a scrolled clip.

Approval Request Comment
[Feature/regressing bug #]: APZ
[User impact if declined]: parts of some pages missing after scrolling, e.g. on http://steamcommunity.com or on http://meetup.com/ .
[Describe test coverage new/current, TreeHerder]: this patch adds a test
[Risks and why]: extremely low risk, extremely small patch. The patch just turns off an optimization in the case where the optimization is wrong.
[String/UUID change made/needed]: none

	Markus Stange [:mstange] Assignee
	Comment 8 • 8 years ago

On meetup.com the steps to reproduce are:
0. Be on OS X with overlay scrollbars enabled.
1. Go to http://www.meetup.com/Toronto-Winter-And-Summer-Trips-Activities/
2. Scroll down and wait for a second.
3. Scroll back up.

The whole header turns white for a moment.

	Ritu Kothari (:ritu) (Inactive, please n-i to RyanVM, jcristau, or pascal)
	Comment 9 • 8 years ago

Hi Markus, could you please verify this issue is fixed as expected on a latest Nightly build? Thanks!

	Markus Stange [:mstange] Assignee
	Comment 10 • 8 years ago

Sure. Just tested, it's fixed.

	Ritu Kothari (:ritu) (Inactive, please n-i to RyanVM, jcristau, or pascal)
	Comment 11 • 8 years ago

Comment on attachment 8778039 [details]
Bug 1259872 - Don't cull all layers under an opaque layer that covers the container if that layer has a scrolled clip.

APZ related regression, Fix has stabilized on Nightly for 2 weeks, Aurora50+, Beta49+

	Ritu Kothari (:ritu) (Inactive, please n-i to RyanVM, jcristau, or pascal)
	Comment 12 • 8 years ago

(In reply to Markus Stange [:mstange] from comment #10)
> Sure. Just tested, it's fixed.

Great Thanks!

	Ryan VanderMeulen [:RyanVM]
	Comment 13 • 8 years ago
bugherder uplift

https://hg.mozilla.org/releases/mozilla-aurora/rev/8194b6ebcb72

	Ryan VanderMeulen [:RyanVM]
	Comment 14 • 8 years ago
bugherder uplift

https://hg.mozilla.org/releases/mozilla-beta/rev/ec3fd2a8ca6d