1483649 - Clicking the X button to stop loading a page will fill it with white background on RTL locales

Status: VERIFIED FIXED

(Core :: Web Painting, defect, P2)

Description

[Itiel]

Attachment: Screencast

Using Windows 10 x86, latest Nightly.

STR:
1. Launch latest Nightly with intl.uidirection set to 1
2. Open any website, preferably a one that takes time to load
3. Click the X button on the toolbar to stop loading the page

AR:
White background underneath the already-clicked X button

ER:
No white background.
This happens only on a mouse click; pressing Esc doesn't make this issue reappear.

Regression range is 2018-07-18 to 2018-07-19.

2018-08-15T21:03:58: DEBUG : Starting merge handling...
2018-08-15T21:03:58: DEBUG : Using url: https://hg.mozilla.org/integration/autoland/json-pushes?changeset=92bd3b2178623a036ea91990aa5570e039890ff4&full=1
2018-08-15T21:03:59: DEBUG : Found commit message:
Bug 1462672 - Part 8: Flatten inactive nsDisplayTransform items r=mattwoodrow

See attached.

Comment 1

[(inactive) Nihanth Subramanya [:nhnt11]]

Attachment: Testcase

Miko, this is a (relatively) minimal testcase that reproduces this bug. Maybe you can reduce it further. You'll need to enable remote XUL. I tested this by toggling layout.display-list.flatten-transform on MacOS in my Nightly build from 2018-08-16. Hope this helps, happy debugging!

Comment 2

[(inactive) Nihanth Subramanya [:nhnt11]]

Attachment: Testcase 2

Got rid of a few more styles that seem irrelevant to the bug.

Comment 3

[Miko Mynttinen]

Thank you for the reduced testcase.

The testcase has two transformed elements, a XUL box and a XUL image. The transform for the XUL box is flattened and the box is drawn on the root painted layer.
Because the XUL image also has an animation set, the transform flattening is disabled, and an active layer is created. When the layer background color is selected, the display items that are inside flattened effects are skipped (the XUL box in this case), and a wrong background color is set.

Including flattened effect markers in ContainerState::FindOpaqueBackgroundColorInLayer() loop should fix this, because nsDisplayTransform::IsUniform() and nsDisplayOpacity::IsUniform() both return Nothing(), and thus force a transparent background.

Comment 4

[Miko Mynttinen]

Attachment: Bug 1483649 - Do not skip display items for flattened effects in ContainerState::FindOpaqueBackgroundColorInLayer

The area covered by flattened effects and their children should be considered in the background color selection to avoid defaulting to canvas background color.

Comment 5

[Matt Woodrow (:mattwoodrow)]

Comment on attachment 9002547 [details]
Bug 1483649 - Do not skip display items for flattened effects in ContainerState::FindOpaqueBackgroundColorInLayer

Matt Woodrow (:mattwoodrow) has approved the revision.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/19eadd36bbba
Do not skip display items for flattened effects in ContainerState::FindOpaqueBackgroundColorInLayer r=mattwoodrow

Comment 7

[Dorel Luca [:dluca]]

https://hg.mozilla.org/mozilla-central/rev/19eadd36bbba

Comment 8

[Itiel]

Looking good on latest Nightly.