34404 - [LIST][MARGIN-C]margins collapse through empty list items despite markers

Status: VERIFIED DUPLICATE of bug 50480

(Core :: Layout, defect, P3)

Description

[Bernd Mielke]

In the attached file, the ordered list start is not a number but a letter, so it 
should be ignored, the list should be 1.2.3.. This is exactly the case for NV 
4.6, Amaya and so on. Furthermore if you load that file in the composer it will 
show the correct list, only in the browser itself and the viewer.exe the list 
collapses to a point. This bug is in a debug build from 04032000 and also in a 
nb1b 2000032205.

Comment 1

[Bernd Mielke]

Attachment: testcase

Comment 2

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

It looks like the list is collapsing to a point because the margins are
collapsing through it.  The list marker needs to be considered for inline box
height to prevent the margins from collapsing through.

Confirming bug.

Comment 3

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

This has absolutely nothing to do with the start='y', which is ignored.  It's
because the list items are empty.  Attaching simpler testcase and retitling.

Comment 4

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

Attachment: simpler testcase

Comment 5

[rickg]

The content model is wellformed. This appears to be a layout bug for buster 
Cousteau. 

Comment 6

[buster]

pushed out to M18

Comment 7

[buster]

redistributing bugs across future milestones, sorry for the spam

Comment 8

[buster]

I'll attach partial frame dumps that show a 2-item list (both items empty).  The 
first one has end tags for the LI, the second one has no end tag for the second 
LI only. 

1st, displays correctly:
<ol>
<li></li>
<li></li>
</ol>

2nd, displays poorly with second item overwriting first:
<ol>
<li></li>
<li>
</ol>

Comment 9

[buster]

Attachment: frame dumps

Comment 10

[Hixie (not reading bugmail)]

This is really an issue with how we place our marker boxes. Per the specs, or
at least per a liberal interpretation of the specs, if you have a list-item
box then the marker will be placed level with the first line box, and if you
do not have a line box then it presumably creates a 'virtual' line box in the 
first empty block, and aligns with that. So a list-item block can never be
empty and thus the top and bottom margins of a list-item block can never be
adjacent. It might be easier just to set min-height:1em on LIs in ua.css...

Comment 11

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

Consolidating issue into one bug...


*** This bug has been marked as a duplicate of 50480 ***

Comment 12

[Hixie (not reading bugmail)]

rubberstamp verified duplicate; this will be revisited when fixing bug 54979.