1497990 - Block end margin of the last child in a column container sometimes gets carry out

Status: RESOLVED FIXED

(Core :: Layout: Columns, defect, P3)

Description

[Ting-Yu Lin [:TYLin] (PDT, UTC-7)]

Attachment: block-end-margin.html

Steps to reproduce:
Open the attached test case.

Expected result:
One green rectangle.

Actual result:
Two green rectangles.


Note: if changing the column-count to 1 or div:last-child's margin-bottom to 16px, the result is expected. 

So I suspect this is something related to our column balancing code.

Comment 1

[Ting-Yu Lin [:TYLin] (PDT, UTC-7)]

Attachment: block-end-margin.html

This is the correct test case to reproduce the issue.

Comment 2

[Ting-Yu Lin [:TYLin] (PDT, UTC-7)]

David, is it correct that that no matter how we handle the margin-bottom of the last child (bug 1487927), the margin-bottom of the last child should not collapse with the column container's margin-bottom like this?

Comment 3

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

Yes, this margin should not get carried out (and the pass condition in the test looks correct), and I think that follows from the resolution in https://github.com/w3c/csswg-drafts/issues/2582 that column boxes create a block formatting context (BFC).

Comment 4

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

Also, if it's a result of column-balancing, it may be related to bug 1487927 and https://github.com/w3c/csswg-drafts/issues/3073

Comment 5

[Ting-Yu Lin [:TYLin] (PDT, UTC-7)]

Attachment: Bug 1497990 Part 1 - Use mIsBalancing instead of comparison between mBalanceColCount with INT32_MAX.

Comment 6

[Ting-Yu Lin [:TYLin] (PDT, UTC-7)]

Attachment: Bug 1497990 Part 2 - Do not carry block-end margin out of ColumnSetFrame.

Depends on D8782

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/7ab933887623
Part 1 - Use mIsBalancing instead of comparison between mBalanceColCount with INT32_MAX. r=dbaron
https://hg.mozilla.org/integration/autoland/rev/730a64fdde3e
Part 2 - Do not carry block-end margin out of ColumnSetFrame. r=dbaron

Comment 8

[Web Platform Test Sync Bot (Matrix: #interop:mozilla.org)]

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/14011 for changes under testing/web-platform/tests

Comment 9

[Web Platform Test Sync Bot (Matrix: #interop:mozilla.org)]

Upstream web-platform-tests status checks passed, PR will merge once commit reaches central.

Comment 10

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/7ab933887623
https://hg.mozilla.org/mozilla-central/rev/730a64fdde3e

Comment 11

[Web Platform Test Sync Bot (Matrix: #interop:mozilla.org)]

Upstream PR merged

Comment 12

[Mohammad Maruf Rahman]

I have reproduced this bug with Nightly 64.0a1 (2018-10-10) on Windows 7, 64 Bit! This bug's fix is verified with latest Beta 65.0b10!

Build ID : 20190110221328
User Agent : Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:65.0) Gecko/20100101 Firefox/65.0