1582548 - mix-blend-mode renders the page white when made visible, depending on CSS

Status: RESOLVED WORKSFORME

(Core :: Graphics: Layers, defect, P3)

Description

[Hallo89]

Attachment: Bug visualisation

Any element with the CSS property of mix-blend-mode (any value) renders the whole document blank for a minimum of a few seconds when being made visible via display: block after it had a display value of none.
However, this is weirdly dependent of some CSS values:

• When the blend-mode element has a value of position: absolute, it only affects itself (and in case of the attachment, only the first button which has been clicked, for some reason)
• When the body has no overflow, it affects the whole page like described above. When it has scrollbars (even inactive ones), no error occurs whatsoever
• Probably some more properties influencing this, but those are the ones that I found

I have created a test case with all those variables toggle-able in the attachment: the black box is just random content, the gray box is the box with mix-blend-mode: difference applied.

I don't like to talk about a repaint because it just seems to be stuck somewhere, but one can always force it to refresh instantly by actually repainting the document, for example when hovering over the devtools DOM inspector (making the blue outline of the element appear) or invoking some hover effect (e.g. the buttons).

This bug does also appear on Firefox Release 69

Comment 1

[Jamie Nicol [:jnicol]]

Thanks for the report and the test case!

Here is the regression range: https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=00bdc9451be6557ccce1492b9b966d4435615380&tochange=071ee904485e21e19ca08456d32bce6825b77a26

Some of Matt's invalidation changes look suspicious to me.

Disabling layout.display-list.retain makes the problem go away.

Comment 2

[Hallo89]

Using a browser emulator (https://www.browserling.com), I have tracked down the issue to have been first introduced in Firefox 62. I can also confirm that it's occurring on both win32 and win64.

Comment 3

[Hallo89]

Using a browser emulator (https://www.browserling.com), I have tracked down the issue to have been first introduced in Firefox 62. I can also confirm that it's occurring on both win32 and win64.

win32 on a 64bit machine, that is

Comment 4

[Hallo89]

This bug seems to have been resolved in Firefox 75. Can I somehow close it myself, or should I always ping the triage owner?