Affected versions

• 85.0a1(2020-12-10), 84.0; 78.6esr;

Affected platforms

• Windows 10, macOS 10.15, Ubuntu 18;

Steps to reproduce

1. Launch Firefox, adjust browser, scale or resolution so that the 1st carousel is just barely visible;
2. Scroll down a bit and hover over a movie-tile so it's open up and preview plays;
3. (quickly)Hover over tile next to it and scroll up;

Expected result

• main-top section of the website is displayed;
• preview stops playing;

Actual result

• the previously hovered tile is still visible & preview is still playing;

Regression range

• fairly hard to assess this, but it's not a regression;
• on older builds, where playback of Netflix is not supported the issue appears not to trigger;

Additional notes

• S3/S4 as suggested severity since it's possible to reset in-page;
• it manifests ~80% of the time, main point being that from how the site is build, if the carousel tile is displayed less than 50% the preview should not be triggered or remain in view;
• attached shortened recording to best illustrate the issue - also updated full recording here;
• checked with other browsers, but the issue does not manifest and tiles seem to reset instant.

Attaching another variation of what appears to be caused by the same issue, received from :mberlinger while confirming the issue is not limited to my workstations.

It seems they're using pointerleave events and such to handle this. Maybe we're not dispatching pointerleave correctly after scroll the same way we synthesize mouse events after scroll?

Setting hightened severity and priority due this being a high-visibility site.

smaug, do you know who would be an appropriate person to investigate this?

Hmm. Now that I tried this myself, I can't even repro. It looks like I mistook the attached animation as suggesting this was worse than it is.

Reporter, can you still repro?

What are the exact steps to reproduce?
If I load netflix.com, I don't see any carousel UI. Does on need to be logged in? (I don't have a netflix account)

Yeah, you need to be logged in... This is my attempt to come up with something close, but I suspect there's something else going on since we do end up dispatching the pointerLeave event correctly on mousemove...

It might be worth trying to contact Netflix if we have a partner list with them before spending too much time trying to reverse-engineer their code?

I tried to repro again (on Mac) and couldn't.

With macOS a few minutes into this, I wasn't able to reproduce either.
As far Win10 goes; it still happens after the 4th attempt, with the above-mentioned steps - Firefox Nightly from 2020-12-18.

Ah, one more thing that I just noticed that isn't noted....might be the most important.
Encountering this issue most often with using the TV as a monitor @ 1080 1920x1080 screen resolution.