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RE: [css3-regions] regions forming stacking contexts

From: Alex Mogilevsky <alexmog@microsoft.com>
Date: Tue, 31 Jan 2012 23:12:59 +0000
To: Vincent Hardy <vhardy@adobe.com>, fantasai <fantasai.lists@inkedblade.net>
CC: "www-style@w3.org" <www-style@w3.org>
Message-ID: <D51C9E849DDD0D4EA38C2E539856928412E28AAF@TK5EX14MBXC218.redmond.corp.microsoft.com>
I thought about it. It seems both ways should be possible, and the argument about regions being low-level building blocks is good. 

It will be easier for me to agree if I see an example where regions render atomically (as would be expected when regions are used as pages). Is it possible to achieve with existing options? Will it be enough to make regions 'position:relative' (I don't think so, just checking)? Or some properties on root of named flow?

Understanding the stacking context is not my strongest skill, but from what I know I don't see any way to create a region with its own stacking context. Perhaps we'll need a property to control that...

Alex

-----Original Message-----
From: Vincent Hardy [mailto:vhardy@adobe.com] 
Sent: Tuesday, January 31, 2012 4:36 AM
To: fantasai
Cc: www-style@w3.org
Subject: Re: [css3-regions] regions forming stacking contexts

Hi Fantasai,

I have looked into this and discussed it with Alex, David Hyatt, Alan Stearns and our implementation team. There are various opinions.

Our team believes that since we see regions as a low level building block, which, for example, could be used (internally) to implement multi-col, indeed, the rendering model should be no different and we could/should make the change you suggest.

Alex thinks differently but I'll let him make his argument. 

Vincent.

On Dec 27, 2011, at 1:58 AM, fantasai wrote:

>   # Regions create a new stacking context. [...]
>   # With regions, an element may be split across multiple regions and these
>   # regions may overlap (for example if they are absolutely positioned).
>   # So fragments of the same element can overlap each other.
>   # Since each element has a single z-index, it would be required to find
>   # another mechanism to decide in which order the fragments are rendered.
>   # Since each region creates a new stacking context, it is clear that each
>   # region is rendered separately and their rendering order follows the
>   # regular CSS rendering model.
> 
> Fragments of the same element can overlap each other already due to 
> inline breaking, so this situation is not unique to regions.
> 
> Unless there's some compelling reason why they should be different, I 
> think I'd rather regions "followed the regular CSS rendering model" as 
> you say at the end... and did not create a new stacking context unless 
> other CSS properties on the region dictated it.
> 
> ~fantasai
> 
Received on Tuesday, 31 January 2012 23:14:00 GMT

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