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Re: overflow and list-items

From: David Hyatt <hyatt@apple.com>
Date: Tue, 22 Jul 2008 16:23:01 -0500
To: Arron Eicholz <Arron.Eicholz@microsoft.com>
Cc: "www-style@w3.org List" <www-style@w3.org>
Message-id: <DF8EDC10-61A4-4037-8938-54AFBC11FBB0@apple.com>

On Jul 22, 2008, at 4:12 PM, David Hyatt wrote:

>
> On Jul 21, 2008, at 7:55 PM, Arron Eicholz wrote:
>
>>
>>> When a 'li' element or any element set to 'display: list-item' has
>>> a setting for 'overflow' other than 'visible' what should happen to
>>> the marker box when it is set to 'list-style-position: outside'?
>>>
>>> Should the marker be visible?
>>>
>>> Should the marker scroll with the first text item even though the
>>> marker is not inside of the scrollable region?
>>
>> Testcases:
>> http://lists.w3.org/Archives/Public/www-archive/2008Jul/att-0050/list-item-overflow-scroll.htm
>> http://lists.w3.org/Archives/Public/www-archive/2008Jul/att-0050/list-item-overflow-visible.htm
>> http://lists.w3.org/Archives/Public/www-archive/2008Jul/att-0050/list-item-overflow-hidden.htm
>>
>> Opera, Safari, and Firefox do not display the marker. However IE7  
>> does.
>> We think it makes more sense to display the marker, so we propose the
>> following:
>>
>> Add to definition of 'outside':
>>  | 'overflow' on the element does not clip the marker box.
>>  | The marker box is fixed with respect to the principal block
>>  | box's border and does not scroll with the principal block
>>  | box's content.
>
> I strongly disagree with this conclusion.  The marker is still  
> conceptually part of the contents of the list item, and the rules  
> for clipping are quite clear.  In order to special case this, you  
> would have to specify a unique position for when outside list  
> markers render in the stacking order (Appendix E).  A sentence in  
> Appendix E also seems to contradict your conclusion:
>
> "For example, an outside list marker comes before an adjoining  
> ':before' box in the line box, which comes before the content of the  
> box, and so forth."
>
> In WebKit an outside list marker is actually in the line box so that  
> it can affect the height of the line.  It is simply translated such  
> that its x position is offset to an outside position.
>
> If the marker has to be rendered before the clip is even applied,  
> you are raising a bunch of other questions at the same time.  For  
> example is the marker affected by opacity?  If so you've created an  
> implicit order between when opacity is applied and when overflow is  
> applied.  (Opacity would have to be applied first.)
>
> If the marker has to render before clipping is applied, then it has  
> to render at a different position in the stacking order than I think  
> most browsers are used to.
>
> I think it makes more sense not to special case the marker and to  
> have it respect the overflow rules like everything else does.

You should also be testing what happens when the 'clip' property is  
applied to a list-item with an outside marker. I would expect  
consistency between 'clip' and 'overflow' here (and my own opinion is  
that both should clip the marker).

dave
(hyatt@apple.com)
Received on Tuesday, 22 July 2008 21:23:47 GMT

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