1669647 - The background of a certain iframe is not steady in Print preview

Status: NEW

(Core :: Print Preview, defect)

Description

[Anca Soncutean, Desktop QA]

Attachment: screencast issue.gif

Affected versions

• 83.0a1 (2020-10-06)
• 82.0b7

Affected platforms

• Ubuntu 18.04

Steps to reproduce

1. Launch Fx
2. Make sure print.tab-modal.enabled is set on true
3. Open https://bug1286622.bmoattachments.org/attachment.cgi?id=8770666
4. Right click on the iframe - This Frame - Print Frame or paste Document.getElementById("iframe").contentWindow.print() inside the web console
5. Change the Destination to your actual printer, the Orientation to Landscape mode and check the Print backgrounds option. if not already set
6. Scroll down a little bit

Expected result

• The background should be steady

Actual result

• The background moves while the print preview is scrolled

Regression range

• Not a regression, visible only with the new UI

Additional notes

• On paper the background is not displayed

Suggested severity

• S4

Comment 1

[Sean Voisen (:svoisen)]

Not reproducible on macOS for me. Will set to P3 for now.

Emilio: Any idea why a fixed background is behaving this way in print preview?

Comment 2

[Emilio Cobos Álvarez (:emilio)]

I can't repro on Linux either, but I suspect that background-attachment: fixed should just be ignored (or fix the background to the page, which I think it's equivalent since the page can't scroll) for print preview, and my guess is that we're fixing to the viewport.

Comment 3

[Sean Voisen (:svoisen)]

Anca: Is this still reproducible for you in the latest Nightly?

Comment 4

[Anca Soncutean, Desktop QA]

(In reply to Sean Voisen (:svoisen) from comment #3)

Anca: Is this still reproducible for you in the latest Nightly?

Yes, this is still reproducible on my side with Fx 84.0a1 (2020-11-09) on Ubuntu 18.04.