809794 - 1 device pixel gap (at different zoom levels) between border of containing element and contained element

Status: UNCONFIRMED

(Core :: Layout, defect)

Description

[Benedikt Pfeifer]

Attachment: Screenshot 1

There's a gap between the border of an element and another element that is 1 device pixel wide on most of the zoom levels (i.e. the gap doesn't scale with the zoom level). I don't see how that could be caused by CSS, so I'm suspecting that it is a rendering bug.

Screenshot 1: the gap is between the blue border of the speech bubble and the background of the span that shows the nickname. I've added a black pixel at the right end of the gap to show it's width. The number at the bottom is the zoom level (in steps of Ctrl+"+").

(Note that neither the mismatched border-radius (we're fixing that already) at the top left nor the poorly scaled bitmap that can also be seen on this image are of concern here).

If the source of such an example would help, I could attach it too (we've got plenty of that since this occurs on the default chat theme of Instantbird;).

Comment 1

[Benedikt Pfeifer]

Sorry, wrong direction for the dependency there..

I assume "16 Branch" is correct when Instantbird using Gecko 16.0.2?

Comment 2

[Florian Quèze [:florian]]

This is apparently very visible on Windows. I don't see it on Mac.

Comment 3

[Boris Zbarsky [:bzbarsky]]

Yes, the source would be very helpful.  A minimal testcase even more so.

Comment 4

[Benedikt Pfeifer]

Attachment: Minimal testcase

It seems different from what I initially reported. The gap depends on the font being used in the inner span (I think I saw a different bug about this already but I can't find it again). See the test case that I have created for this.

Comment 5

[Benedikt Pfeifer]

Attachment: Screenshot of the test case

Here's a screenshot of the test case.
The large section is at maximum zoom level, the small inset is unzoomed.