STR:

1. Load https://www.macrumors.com/.
2. Scroll down to an entry that embeds a tweet where the embedding iframe is behind the "Show Full Article" button.
3. Mouse over the "Show Full Article" button.
4. Click the button.

Expected results:

1. When mousing over the button, it is immediately highlighted and the cursor changes to a hand.
2. When clicking the button, the full macrumors.com article is opened.

Actual results:

1. When mousing over the button, it is highlighted only after a ~0.5s delay and the cursor does not change.
2. When clicking the button, the tweet is opened.

The title of the entry in question is "Reliable Leaker Suggests Redesigned MacBooks in 2021 Will Include Both Apple Silicon and Intel Models". Oddly my daily use nightly does just show the tweet text and is not able to reproduce the issue. But on my local build, it shows embedded tweet image, then is able to reproduce the issue. I am attaching a screenshot of the entry. (I took it without fission, since with enabling fission, the tweet image were not rendered in the screenshot)

Looks like the text tweet case on my daily use nightly, the tweet content is not iframe-ed at all. I don't know where the difference comes from.

Probably this is a minimum test case, there is an OOP iframe inside a containing block and there is a a position:absolute element inside the containing block and the element has an <a>.

CCing Timothy. (I have totally no idea how we treat this kind of overlapping elements in APZ)

Timothy, this is really bad, can you fix this please?

Redirecting need info to Botond as I believe he is currently working on fission hit testing issues.

I believe Miko is already looking into similar hit testing issues for Fission (thanks Miko).

Botond said he'll look into this.

I am ~100% sure this is a dup of bug 1676466. (I hadn't noticed the bug before)

Thanks Hiro! I'll mark bug 1676466 as a dependency, and we'll re-test once that is fixed.

Miko, can you test this with your patch for bug 1676466 to see if it fixes this?

(In reply to Neha Kochar [:neha] from comment #11)

Miko, can you test this with your patch for bug 1676466 to see if it fixes this?

It does. :)