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Re: [CSS21] stack level definitions in 9.9.1

From: Anton Prowse <prowse@moonhenge.net>
Date: Fri, 06 Jun 2008 00:21:48 +0200
Message-ID: <484866FC.6060804@moonhenge.net>
To: www-style@w3.org

Anton Prowse wrote:
 > There are (at least) eight ambiguities or errors in description in 
9.9.1 of stacking contexts, stacking levels and z-index

 > http://dev.moonhenge.net/css21/spec/z-index/

I have added to this collection the following issue, which has urgency 
in that the behaviour of the first beta release of IE8 differs from all 
other major browsers and yet cannot be said to be violating the current 
specification.

Within a given stacking context, 9.9.1 mandates separate "stacking 
levels" (painting layers) for positioned elements (three layers, 
corresponding to negative/positive/auto-0 z-index) and floats (one 
layer).  However, it fails to specify whether relatively positioned 
floats fall into the painting layer for floats or into the appropriate 
painting layer for relatively positioned elements.

IE8b1 decides that floats belong in the float layer, irrespective of 
position or z-index.  Everybody else (including IE<=7) allows position 
to win out over float.  The latter approach is of course preferable 
because IE8b1's approach renders the z-index property impotent for 
relatively positioned floats.

It would be desirable to resolve this issue or discuss it with Microsoft 
before IE8 is finalized.  The corresponding bug report for IE8 is 
https://connect.microsoft.com/IE/feedback/ViewFeedback.aspx?FeedbackID=348959 
  (registration required).

Thanks,

Anton Prowse
http://dev.moonhenge.net
Received on Thursday, 5 June 2008 22:22:01 GMT

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