1638285 - Incomplete painting of Firefox window on windows switching

Status: RESOLVED DUPLICATE of bug 1637497

(Core :: Graphics: WebRender, defect)

Description

[Alexander Grimalovsky]

Attachment: Application switch demonstration with mozilla.com website

Firefox Developer Edition 77.0b6 on Windows 7 Pro x64 running on Dell Precision M4800.

Steps to reproduce:

1. Run Firefox and some other application, expand both or otherwise let other application to cover Firefox window when in focus
2. Open any site in Firefox
3. Switch to other application, either through Alt+Tab or by clicking on task bar
4. Switch back to Firefox

Expected behavior: Firefox displays its window and site in it

Actual behavior: Firefox's window is painted incompletely, painting of remaining areas occurs in a case of any interaction, e.g. window scrolling

Firefox 76 and below are not affected, behavior is specific for Firefox 77 branch. Actual sites results into painting problems all the time while empty tab or system pages like about:addons are much less affected.

Please find attached GIF animations with recorded examples of the issue.

Comment 1

[Alexander Grimalovsky]

Attachment: Application switch demonstration with "new tab"

Comment 2

[Alexander Grimalovsky]

Attachment: Application switch demonstration with about:addons system page

Comment 3

[Alexander Grimalovsky]

Please let me know if I should provide any additional information or do some other tests that may help you.

Comment 4

[Florian Quèze [:florian]]

Hello,

Which operating system are you using? The bug indicates "Windows 7", is this correct?
You said you see the problem on Firefox 77 but not 76 so this sounds like a regression. Would you be able to use mozregression to find a regression range for this? That'd be extremely helpful to pin down what caused it.

Comment 5

[Alexander Grimalovsky]

Florian It is Windows 7 Professional SP1, build 7601, patched with all official updates from Microsoft up to the end of support for Windows 7 from them.

Use of mozregression allows finding exact issue that caused a reported issue (bug 1636482, pushlog report from mozregressio), but looking at it I doubt that this particular issue is somehow helpful by itself.

Can I help you further to try to find reason of this issue? If yes - please guide me.

Comment 6

[Alexandru Trif, Desktop Test Engineering [:atrif]]

It seems that Firefox 78.0a1 (20200525093440) on Windows 7x64 is no longer affected by this. After searching for a fix range I found bug 1638469.

Also searching for a regression range with WebRender enabled gave me this pushlog: link.

Comment 7

[Darkspirit]

Thanks for narrowing this down!

Comment 8

[Alexander Grimalovsky]

I've checked nightly build from 2020-05-25 (built from) and can confirm that it is not affected by this issue.