1460482 - Force root scrollframe overlay scrollbars to be positioned and on top of all content

Status: RESOLVED FIXED

(Core :: Web Painting, enhancement, P2)

Description

[Matt Woodrow (:mattwoodrow)]

Overlay scrollbars disable retained-dl, since their z-index positioning depends on the other content built in the display list.

For the root scrollframe, we should just be able to always force their scrollbars to z-index:INT32_MAX without issue, and then we have deterministic positioning.

Comment 1

[Matt Woodrow (:mattwoodrow)]

Attachment: Bug 1460482 - Force root scroll frame overlay scroll bars to be always on top.

Review commit: https://reviewboard.mozilla.org/r/242970/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/242970/

Comment 2

[Markus Stange [:mstange]]

Comment on attachment 8974604 [details]
Bug 1460482 - Force root scroll frame overlay scroll bars to be always on top.

https://reviewboard.mozilla.org/r/242970/#review249052

Comment 3

[Matt Woodrow (:mattwoodrow)]

Comment on attachment 8974604 [details]
Bug 1460482 - Force root scroll frame overlay scroll bars to be always on top.

Review request updated; see interdiff: https://reviewboard.mozilla.org/r/242970/diff/1-2/

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/fd3cab8c506a
Force root scroll frame overlay scroll bars to be always on top. r=mstange

Comment 5

[Eliza Balazs [:ebalazs_]]

https://hg.mozilla.org/mozilla-central/rev/fd3cab8c506a

Comment 6

[Alexandru Simonca [:asimonca], Release Desktop QA]

Is manual testing required for this fix? 
If yes, could you please provide some clear steps on how we can check this?

Thank you.

Comment 7

[Matt Woodrow (:mattwoodrow)]

No, this shouldn't need verification, it was just an internal optimization.

Comment 8

[Alexandru Simonca [:asimonca], Release Desktop QA]

Thanks for the prompt answer. Changing the flag accordingly.