Affected versions

• Fx. 82.0b8

Affected platforms
*Ubuntu 18.04

Steps to reproduce

1. Open multiple tabs
2. Open photo warp
3. Warp the photo so that the background is visible.
4. Close Firefox by clicking on X.

Expected result

• When the Close multiple tabs modal appears, the background should stay grey.

Actual result

• When the Close multiple tabs modal appears, the background of the photo becomes transparent, revealing what is behind the browser.

Suggested Severity

• S3 because while a weird bug, its a visual bug that occurs under certain conditions on ubuntu.

Regression range
I will return with a regression range ASAP.

The severity field is not set for this bug.
:jgilbert, could you have a look please?

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Compositing bug? Maybe an RGBA canvas that's not being blended, but overwriting the window's alpha channel?

As long as this is indeed just showing what's "behind" the window, this isn't actually dangerous, but it's an annoying bug that could cause certain use cases to break.

Might be compositing, but I've also seen this before when an image was marked as RGBX/opaque, but actually contained transparency.

Yeah it's possible that this happens somewhere in the webgl->CanvasRenderer glue.

That's a combination of RGBA visual and active opaque region - background is visible because we set the window as non-transparent so window manager does not draw window background by default.

Generally it's missing background of canvas element.

On the balance I feel like this is more a compositing issue than a webgl issue.

Anyone know if this still reproduces? The bug was reported against 82.

gw says it's WORKSFORME