W3C home > Mailing lists > Public > www-style@w3.org > August 2009

Re: Shadows vs. layout

From: Andrew Fedoniouk <news@terrainformatica.com>
Date: Mon, 03 Aug 2009 13:17:54 -0700
Message-ID: <4A7745F2.2080701@terrainformatica.com>
To: David Hyatt <hyatt@apple.com>
CC: fantasai <fantasai.lists@inkedblade.net>, Brad Kemper <brad.kemper@gmail.com>, W3C style mailing list <www-style@w3.org>
David Hyatt wrote:
> On Aug 3, 2009, at 12:23 PM, fantasai wrote:
> 
>> I completely agree. Added
>>  "Shadows never affect layout, and do not trigger scrolling."
>> to the spec, hopefully that's clear enough.
> 
> I strongly disagree with this change and think it warrants further 
> discussion.
> 
> Shadows in WebKit are visual overflow.  If you put a box-shadow on an 
> object near the bottom of a document, you'd expect to be able to scroll 
> to see that shadow.  It shouldn't simply be cut off.  I see no reason 
> why shadows would be special cased versus all of the other kinds of 
> visual overflow that can occur on a page.
> 
> Shadows are clipped if they spill out of a box with overflow:hidden 
> specified. They are obviously overflow.  Why should overflow:scroll/auto 
> deliberately ignore this overflow just when scrolling? That makes no 
> sense to me, and is more memory-intensive to code.  You're saying the 
> engine has to track shadows as visual overflow for the purposes of 
> accurate container repainting, but then somehow track a completely 
> second set of visual overflow numbers that exclude shadows just to 
> ensure that you don't include shadow overflow when scrolling?  That's nuts.
> 
> dave
> (hyatt@apple.com)
> 
> 
> 

Shadows and other types of outlines do not affect neither box
dimensions nor dimensions of its container nor dimensions of
scrollable content. By definition. (space/time and so on).

E.g. window shadow is not causing scroll of desktop window not on Mac
not on Windows and not on any other GUI system I know about.

-- 
Andrew Fedoniouk.

http://terrainformatica.com
Received on Monday, 3 August 2009 20:18:28 GMT

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