Add :valid-drop-target.

Author: tabatkins

selectors4/Overview.html

@@ -276,6 +276,10 @@ <h2 class="no-num no-toc" id=contents>Table of Contents</h2>
 
      <li><a href="#focus-pseudo"><span class=secno>8.3. </span> The input
       focus pseudo-class ‘<code class=css>:focus</code>’</a>
+
+     <li><a href="#the-valid-drop-target-pseudo"><span class=secno>8.4.
+      </span> The drag-and-drop pseudo-class
+      <code>:valid-drop-target</code></a>
     </ul>
 
    <li><a href="#time-pseudos"><span class=secno>9. </span> Time-dimensional
@@ -2432,6 +2436,29 @@ <h3 id=focus-pseudo><span class=secno>8.3. </span> The input focus
   <p>There may be document language or implementation specific limits on
    which elements can acquire <code>:focus</code>.
 
+  <h3 id=the-valid-drop-target-pseudo><span class=secno>8.4. </span> The
+   drag-and-drop pseudo-class <a
+   href="#valid-drop-target-pseudo"><code>:valid-drop-target</code></a></h3>
+
+  <p> The <dfn id=valid-drop-target-pseudo>:valid-drop-target</dfn>
+   pseudo-class applies while an element is being hovered over, and is a
+   valid target for the current drag-and-drop operation, as defined by the
+   host language.
+
+  <p class=example> For example, <a href="#HTML5"
+   rel=biblioentry>[HTML5]<!--{{HTML5}}--></a> defines the <a
+   href="http://www.whatwg.org/specs/web-apps/current-work/multipage/dnd.html#the-dropzone-attribute"><code>dropzone</code></a>
+   attribute, which allows an author to declare an element as a "drop
+   target", and declare what kinds of data the element is willing to accept
+   from drag-and-drop.
+
+  <p> If a UA has alternate models of drag-and-drop, such as one based on
+   focusing elements, the <a
+   href="#valid-drop-target-pseudo"><code>:valid-drop-target</code></a>
+   pseudo-class must also match when such an element is interacted with such
+   that the user is about to drop into the element, such as when the
+   <code>:focus</code> pseudo-class applies.
+
   <h2 id=time-pseudos><span class=secno>9. </span> Time-dimensional
    Pseudo-classes</h2>
 

selectors4/Overview.src.html

@@ -1714,6 +1714,27 @@ <h3 id="focus-pseudo">
   <p>There may be document language or implementation specific limits on
   which elements can acquire <code>:focus</code>.</p>
 
+<h3 id='the-valid-drop-target-pseudo'>
+The drag-and-drop pseudo-class <code>:valid-drop-target</code></h3>
+
+  <p>
+    The <dfn id='valid-drop-target-pseudo'>:valid-drop-target</dfn> pseudo-class
+    applies while an element is being hovered over,
+    and is a valid target for the current drag-and-drop operation,
+    as defined by the host language.
+
+  <p class='example'>
+    For example, [[HTML5]] defines the <a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/dnd.html#the-dropzone-attribute"><code>dropzone</code></a> attribute,
+    which allows an author to declare an element as a "drop target",
+    and declare what kinds of data the element is willing to accept from drag-and-drop.
+
+  <p>
+    If a UA has alternate models of drag-and-drop,
+    such as one based on focusing elements,
+    the <code>:valid-drop-target</code> pseudo-class must also match when such an element is interacted with
+    such that the user is about to drop into the element,
+    such as when the <code>:focus</code> pseudo-class applies.
+
 <h2 id="time-pseudos">
 Time-dimensional Pseudo-classes</h2>