BookReader Preview sometimes shows a grey page artifact in 1up

[cdrini]

Eg:

• https://archive.org/details/unknown0000vari_g5u9/mode/1up
• https://archive.org/details/unknown0000vari_b2c2/mode/1up

To Reproduce:

1. Go to one of the erroring cases in 1up mode
2. Scroll down from the top

Expected: You see the preview placeholder when you get to that page
Actual: A preview placeholder appears randomly and obstructs part of the screen.

Context

Can repro on FF 140 + win10

Proposal & Constraints

What is the proposed solution / implementation? Is there a precedent of this approach succeeding elsewhere?

Stakeholders

@seabelis

[cdrini]

I think it might be something to do if the preview includes exactly one page before going to the placeholder pages.

[Gurleen-kansray]

I tested this on Windows 11 with Firefox 142.0, and I couldn’t reproduce the grey preview artifact in 1-up mode on either of the examples provided.

If possible, could you please confirm whether you still see the issue on Firefox 140 (Windows 10)? Alternatively, if there’s a specific zoom level or scroll speed that triggers it, would you mind sharing those details—or perhaps testing again on the same browser version?

Maybe this happens only on Windows 10 — should I test specifically on that OS?