338670 - Exhibits 'rounding-error' like rendering behavior on anchors with 'text-align: center' upon resizing window

Status: NEW

(Core :: Layout, defect)

Description

[Steven Luscher]

User-Agent:       Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en) AppleWebKit/418 (KHTML, like Gecko) Safari/417.9.3
Build Identifier: Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; rv:1.9a1) Gecko/20060520 Minefield/3.0a1

Here we have a series of <li><a href="#">Link</a></li> type markup where the li has 'text-align: center;' on it. The body has 'margin: 0 auto;' on it, effectively centering the page. When I resize the window horizontally, the word "Link" jitters left and right, as though it is falling prey to a rounding-error-like bug.

Please see the attached HTML page for my example.

Reproducible: Always

Steps to Reproduce:
1. Open sample HTML page (attached)
2. Resize window horizontally
3. Whilst resizing, observe the link text jitter left and right

Actual Results:  
The link text will jitter left and right depending on the width of the window.

Expected Results:  
The link text should have stayed fixed in a position relative to its parent.

HTML testcase attached.

Comment 1

[Steven Luscher]

Attachment: HTML testcase exhibiting jittering text bug

Comment 2

[Mike Connor [:mconnor]]

moving to core, you'd need to nominate for blocking 1.8.1 instead

Comment 3

[Mike Schroepfer]

I'm not seeing this behavior on the 1.8 (1.8.1) branch and your useragent indicates you are seeing this on the trunk only.  Clearing 1.8.1 nom.

Comment 4

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

I don't see this on the trunk on Linux, and I don't see any reason to think what you'd be seeing is Mac-only.  Are the actual and expected results not clear enough about which words I need to look at?

Comment 5

[Steven Luscher]

Attachment: Figure One

Comment 6

[Steven Luscher]

Attachment: Figure Two

Comment 7

[Steven Luscher]

Attachment: Figure Three

Comment 8

[Steven Luscher]

Attachment: Figure Four

Comment 9

[Steven Luscher]

OK... I can't get too much more clear than by attaching screenshots with pixel measurements Photoshopped in (in yellow). Watch what happens to the testcase as I resize the window, one pixel at a time, from 1029 px (Figure One) to 1030 px (Figure Two... Oh oh!!!) to 1031 px (Figure Three).

Notice how the relationship between the measurements is the same in Figure One and Figure Three, but different in Figure Two (offending measurement marked in red in Figure Two.

The "About" dialog box is shown also (Figure Four) so you can see which version of Firefox I used to make these observations.

Comment 10

[Steven Luscher]

I just downloaded the Firefox 2.0b1 and this bug is still present. Please take a look at the screenshots that I've uploaded since this bug was posted and read comment #9.

Comment 11

[Frankie]

Confirming that the text spacing still jitters 9 years later.

On Mac: testcase does not jitter in Chrome. However, 2nd to last line jitters in Safari.

Comment 12

[Frankie]

See also similar bug 419402