372053 - [columns] clip column box overflow (or not?)

Status: RESOLVED INVALID

(Core :: Layout: Block and Inline, defect)

Description

[Mats Palmgren (inactive)]

The "CSS3 module: Multi-column layout" spec crrently says that
column box overflow should be clipped (2nd paragraph):
"Content that extend outside the column box ... is clipped. 
... as if the column box had 'overflow:hidden'"
http://www.w3.org/TR/css3-multicol/#the-multi-column

We currently render it as if 'overflow:visible'.
This bug is for tracking this issue, whether the implementation should be
changed to match the spec or vice versa.

Testcase in bug 370974:  attachment 255789 [details]

FWIW, a 2007-02-27 Webkit nightly implements it as 'overflow:hidden'.

Comment 1

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

I think that part of the spec is broken; it's actually been discussed in the WG recently, although there's not a conclusion yet.

Comment 2

[Mats Palmgren (inactive)]

Personally, I think it would make sense to introduce a new property, e.g 'column-overflow', to allow it to be specified. And that the default
should be 'visible' as it is for 'overflow'.

But why introduce all these special column-* properties? why not allow
styling the columns directly using pseudo elements, e.g. ::column(0)

Comment 3

[Mats Palmgren (inactive)]

I saw that column clipping came up [1] in the discussion on multi-column
floats in the [css3-gcpm] spec and again I think it supports the position
that the default should be overflow, not hidden.

[1] http://lists.w3.org/Archives/Public/www-style/2007May/0014.html
[css3-gcpm] http://www.w3.org/TR/2006/WD-css3-gcpm-20060919/

Comment 4

[Oli Studholme]

See also https://bugzilla.mozilla.org/show_bug.cgi?id=531791 “Overflows of non-floated elements not being clipped within -moz-column”

Also, WebKit clips at *column gap edge*, not column box edge as spec states.

Comment 7

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

The working group resolved that columns shouldn't clip:
http://krijnhoetmer.nl/irc-logs/css/20130911#l-950