Add proposed resolution for issue 26.

Author: dbaron

css3-color/Overview.html

@@ -64,18 +64,18 @@
 
    <h1 id=css-color>CSS Color Module</h1>
 
-   <h2 class="no-num no-toc" id=editors>Editor's Draft 13 May 2008</h2>
+   <h2 class="no-num no-toc" id=editors>Editor's Draft 14 May 2008</h2>
 
    <dl>
     <dt>This version:
 
     <dd><a
-     href="http://www.w3.org/TR/2008/ED-css3-color-20080513">http://www.w3.org/TR/2008/ED-css3-color-20080513</a>
+     href="http://www.w3.org/TR/2008/ED-cvs-member-20080514">http://www.w3.org/TR/2008/ED-cvs-member-20080514</a>
 
     <dt>Latest version:
 
     <dd><a
-     href="http://www.w3.org/TR/css3-color">http://www.w3.org/TR/css3-color</a>
+     href="http://www.w3.org/TR/cvs-member">http://www.w3.org/TR/cvs-member</a>
 
     <dt>Previous version:
 
@@ -159,8 +159,8 @@ <h2 class="no-num no-toc" id=status>Status of This Document</h2>
    mailing list <a href="mailto:www-style@w3.org">www-style@w3.org</a> (see
    <a href="http://www.w3.org/Mail/Request">instructions</a>) is preferred
    for discussion of this specification. When sending e-mail, please put the
-   text &#8220;css3-color&#8221; in the subject, preferably like this:
-   &#8220;[<!---->css3-color<!---->] <em>&hellip;summary of
+   text &#8220;cvs-member&#8221; in the subject, preferably like this:
+   &#8220;[<!---->cvs-member<!---->] <em>&hellip;summary of
    comment&hellip;</em>&#8221;
 
   <p>This document was produced by the <a href="/Style/CSS/members">CSS
@@ -628,6 +628,28 @@ <h3 id=transparency><span class=secno>3.2 </span>Transparency: the <span
     mask where the value of each pixel of the mask is &lt;alphavalue&gt;.
   </dl>
 
+  <p>Since an element with opacity less than 1 is composited from a single
+   offscreen image, content outside of it cannot be layered in z-order
+   between pieces of content inside of it. For the same reason,
+   implementations must create a new stacking context for any element with
+   opacity less than 1. If an element with opacity less than 1 is not
+   positioned, implementations must paint the layer it creates, within its
+   parent stacking context, at the same stacking order that would be used if
+   it were a positioned element with &lsquo;<code class=css>z-index:
+   0</code>&rsquo; and &lsquo;<code class=css>opacity: 1</code>&rsquo;. If an
+   element with opacity less than 1 is positioned, the &lsquo;<span
+   class=property>z-index</span>&rsquo; property applies as described in <a
+   href="#CSS21" rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>, except that
+   &lsquo;<span class=property>auto</span>&rsquo; is treated as &lsquo;<code
+   class=css>0</code>&rsquo; since a new stacking context is always created.
+   See <a href="http://www.w3.org/TR/CSS21/visuren.html#layers">section
+   9.9</a> and <a href="http://www.w3.org/TR/CSS21/zindex.html">Appendix
+   E</a> of <a href="#CSS21" rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a> for
+   more information on stacking contexts. The rules in this paragraph do not
+   apply to SVG elements, since SVG has its own <a
+   href="http://www.w3.org/TR/SVG11/render.html">rendering model</a> <a
+   href="#SVG11" rel=biblioentry>[SVG11]<!--{{!SVG11}}--></a>.
+
   <h2 id=colorunits><span class=secno>4. </span>Color units</h2>
 
   <p>A <span class="index-def value-def-color" id=valuea-def-color
@@ -4861,6 +4883,16 @@ <h3 id=normative><span class=secno>11.1 </span>Normative</h3>
     </dd>
    <!---->
 
+   <dt id=CSS21>[CSS21]
+
+   <dd>Bert Bos; et al. <a
+    href="http://www.w3.org/TR/2007/CR-CSS21-20070719"><cite>Cascading Style
+    Sheets, level 2 revision 1.</cite></a> 19 July 2007. W3C Candidate
+    Recommendation. (Work in progress.) URL: <a
+    href="http://www.w3.org/TR/2007/CR-CSS21-20070719">http://www.w3.org/TR/2007/CR-CSS21-20070719</a>
+    </dd>
+   <!---->
+
    <dt id=ICC42>[ICC42]
 
    <dd><a href="http://color.org/ICC1v42_2006-05.pdf"><cite>Image technology

css3-color/Overview.src.html

@@ -425,6 +425,28 @@ <h3 id="transparency">Transparency: the <span class="property">'opacity'</span>
 
 </dl>
 
+<p>Since an element with opacity less than 1 is composited from a
+single offscreen image, content outside of it cannot be layered
+in z-order between pieces of content inside of it.  For the same
+reason, implementations must create a new stacking context for
+any element with opacity less than 1.  If an element with
+opacity less than 1 is not positioned, implementations must
+paint the layer it creates, within its parent stacking context,
+at the same stacking order that would be used if it were a
+positioned element with 'z-index: 0' and 'opacity: 1'.  If an
+element with opacity less than 1 is positioned, the 'z-index'
+property applies as described in [[!CSS21]], except that 'auto'
+is treated as '0' since a new stacking context is always
+created.  See <a
+href="http://www.w3.org/TR/CSS21/visuren.html#layers">section
+9.9</a> and <a
+href="http://www.w3.org/TR/CSS21/zindex.html">Appendix E</a> of
+[[!CSS21]] for more information on stacking contexts.  The rules
+in this paragraph do not apply to SVG elements, since SVG has
+its own <a
+href="http://www.w3.org/TR/SVG11/render.html">rendering
+model</a> [[!SVG11]].</p>
+
 <h2 id="colorunits">Color units</h2>
 
 <p>A