[giow] (0) Updates to anchoring for dialogs.

Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=20418
Affected topics: HTML

git-svn-id: http://svn.whatwg.org/webapps@7644 340c8d12-0b0e-0410-8428-c7bf67bfef74

complete.html

@@ -59646,11 +59646,14 @@ <h4 id=the-dialog-element><span class=secno>4.11.7 </span>The <dfn><code>dialog<
   <p>When an element's 'position' property computes to '<dfn id=css-position-absolute-anchored title=css-position-absolute-anchored>absolute-anchored</dfn>', the 'float' property does not
   apply and must compute to 'none', the 'display' property must compute to a value as described by
   the table in <a href=http://www.w3.org/TR/CSS21/visuren.html#dis-pos-flo>the section of CSS 2.1
-  describing the <cite>relationships between 'display', 'position', and 'float'</cite></a>, and the
-  element's box must be positioned using the rules for absolute positioning but with its static
-  position set such that if the box is positioned in its static position, its anchor point is
-  exactly aligned over the anchor point of the element to which it is <a href=#magically-aligned>magically
-  aligned</a>.</p>
+  describing the <cite>relationships between 'display', 'position', and 'float'</cite></a>, the
+  element's containing block is the initial containing block, and the element's box must be
+  positioned using the rules for absolute positioning but with its static position set such that if
+  the box is positioned in its static position, its anchor point is exactly aligned over the anchor
+  point of the element to which it is <a href=#magically-aligned>magically aligned</a>. Elements aligned in this way
+  are <i>absolutely positioned</i>. For the purposes of determining the containing block of other
+  elements, the '<a href=#css-position-absolute-anchored title=css-position-absolute-anchored>absolute-anchored</a>' keyword must
+  be treated like the 'absolute' keyword.</p>
 
   <p>If an element to which another element is anchored changes rendering, the anchored element must
   be repositioned accordingly. (In other words, the requirements above are live, they are not just
@@ -59660,6 +59663,11 @@ <h4 id=the-dialog-element><span class=secno>4.11.7 </span>The <dfn><code>dialog<
   keyword is not a keyword that can be specified in CSS; the 'position' property can only compute to
   this value if the <code><a href=#the-dialog-element>dialog</a></code> element is positioned via the APIs described above.</p>
 
+  <p class=note>Elements positioned in this way are not clipped by the 'overflow' property of
+  ancestors (nor moved by the resulting scrolling mechanisms). Anchoring to an element that
+  <em>is</em> so clipped (and shifted) can therefore result in unexpected effects (where the
+  anchored element moves along with the clipped element, but isn't itself clipped).</p>
+
   <hr><!--TOPIC:DOM APIs--><p>The <dfn id=dom-dialog-open title=dom-dialog-open><code>open</code></dfn> IDL
   attribute must <a href=#reflect>reflect</a> the <code title=attr-dialog-open><a href=#attr-dialog-open>open</a></code> content attribute.</p>
 <!--TOPIC:HTML-->

index

@@ -59646,11 +59646,14 @@ fur
   <p>When an element's 'position' property computes to '<dfn id=css-position-absolute-anchored title=css-position-absolute-anchored>absolute-anchored</dfn>', the 'float' property does not
   apply and must compute to 'none', the 'display' property must compute to a value as described by
   the table in <a href=http://www.w3.org/TR/CSS21/visuren.html#dis-pos-flo>the section of CSS 2.1
-  describing the <cite>relationships between 'display', 'position', and 'float'</cite></a>, and the
-  element's box must be positioned using the rules for absolute positioning but with its static
-  position set such that if the box is positioned in its static position, its anchor point is
-  exactly aligned over the anchor point of the element to which it is <a href=#magically-aligned>magically
-  aligned</a>.</p>
+  describing the <cite>relationships between 'display', 'position', and 'float'</cite></a>, the
+  element's containing block is the initial containing block, and the element's box must be
+  positioned using the rules for absolute positioning but with its static position set such that if
+  the box is positioned in its static position, its anchor point is exactly aligned over the anchor
+  point of the element to which it is <a href=#magically-aligned>magically aligned</a>. Elements aligned in this way
+  are <i>absolutely positioned</i>. For the purposes of determining the containing block of other
+  elements, the '<a href=#css-position-absolute-anchored title=css-position-absolute-anchored>absolute-anchored</a>' keyword must
+  be treated like the 'absolute' keyword.</p>
 
   <p>If an element to which another element is anchored changes rendering, the anchored element must
   be repositioned accordingly. (In other words, the requirements above are live, they are not just
@@ -59660,6 +59663,11 @@ fur
   keyword is not a keyword that can be specified in CSS; the 'position' property can only compute to
   this value if the <code><a href=#the-dialog-element>dialog</a></code> element is positioned via the APIs described above.</p>
 
+  <p class=note>Elements positioned in this way are not clipped by the 'overflow' property of
+  ancestors (nor moved by the resulting scrolling mechanisms). Anchoring to an element that
+  <em>is</em> so clipped (and shifted) can therefore result in unexpected effects (where the
+  anchored element moves along with the clipped element, but isn't itself clipped).</p>
+
   <hr><!--TOPIC:DOM APIs--><p>The <dfn id=dom-dialog-open title=dom-dialog-open><code>open</code></dfn> IDL
   attribute must <a href=#reflect>reflect</a> the <code title=attr-dialog-open><a href=#attr-dialog-open>open</a></code> content attribute.</p>
 <!--TOPIC:HTML-->

source

@@ -69803,11 +69803,14 @@ fur
   title="css-position-absolute-anchored">absolute-anchored</dfn>', the 'float' property does not
   apply and must compute to 'none', the 'display' property must compute to a value as described by
   the table in <a href="http://www.w3.org/TR/CSS21/visuren.html#dis-pos-flo">the section of CSS 2.1
-  describing the <cite>relationships between 'display', 'position', and 'float'</cite></a>, and the
-  element's box must be positioned using the rules for absolute positioning but with its static
-  position set such that if the box is positioned in its static position, its anchor point is
-  exactly aligned over the anchor point of the element to which it is <span>magically
-  aligned</span>.</p>
+  describing the <cite>relationships between 'display', 'position', and 'float'</cite></a>, the
+  element's containing block is the initial containing block, and the element's box must be
+  positioned using the rules for absolute positioning but with its static position set such that if
+  the box is positioned in its static position, its anchor point is exactly aligned over the anchor
+  point of the element to which it is <span>magically aligned</span>. Elements aligned in this way
+  are <i>absolutely positioned</i>. For the purposes of determining the containing block of other
+  elements, the '<span title="css-position-absolute-anchored">absolute-anchored</span>' keyword must
+  be treated like the 'absolute' keyword.</p>
 
   <p>If an element to which another element is anchored changes rendering, the anchored element must
   be repositioned accordingly. (In other words, the requirements above are live, they are not just
@@ -69817,6 +69820,11 @@ fur
   keyword is not a keyword that can be specified in CSS; the 'position' property can only compute to
   this value if the <code>dialog</code> element is positioned via the APIs described above.</p>
 
+  <p class="note">Elements positioned in this way are not clipped by the 'overflow' property of
+  ancestors (nor moved by the resulting scrolling mechanisms). Anchoring to an element that
+  <em>is</em> so clipped (and shifted) can therefore result in unexpected effects (where the
+  anchored element moves along with the clipped element, but isn't itself clipped).</p>
+
   <hr>
 
 <!--TOPIC:DOM APIs-->