ISSUE-1028: Separator is a structure but the description says it can …

…be interactive

This is largely an editorial clarification with the addition of normative
language for authors. It maintains the ARIA 1.0 idea that a separator can
be either a horizontal rule or an interactive window splitter, but it adds
language that explains how that can be done in a way that will result in
appropriate assistive technology behaviors.

* Add text explaining the two types of separators: structures and widgets
* Separator is now described as a structure if it is not focusable
* Add a normative statement explaining that authors MAY make a separator
  focusable and that if they do, it will be recognized by assistive
  technologies as an interactive widget
* Add normative statement saying authors MAY use aria-expanded to describe
  the state of a separator
* Add normative statement saying authors MAY use aria-valuenow to describe
  the state of a variable separator widget
* Add text describing an example of a variable separator
* Add widget as a superclass (consistent with what was implied in ARIA 1.0)
* Add statement that aria-expanded is supported only if the separator is
  is focusable (consistent with ARIA 1.0)
* Add aria-valuenow, aria-valuemin, aria-valuemax, and aria-valuetext as
  supported properties for variable separator widgets (new for ARIA 1.1)

aria/aria.html

@@ -6112,7 +6112,9 @@ <h5 id="role-presentation-ednote-none">Editorial Note regarding the ARIA 1.1 <rr
 			<rdef>separator</rdef>
 			<div class="role-description">
 				<p>A divider that separates and distinguishes sections of content or groups of menuitems.</p>
-				<p>This is a visible separator between sections of content. For example, separators are found between groups of menu items in a menu or as the moveable separator between two regions in a split pane.</p>
+				<p>There are two types of separators: a static <rref>structure</rref> that provides only a visible boundary and a focusable, interactive <rref>widget</rref> that is also moveable. If a <code>separator</code> is not focusable, it is revealed to <a>assistive technologies</a> as a static structural element. For example, a static <code>separator</code> can be used to help visually divide two groups of menu items in a menu or to provide a horizontal rule between two sections of a page.</p>
+				<p>Authors MAY make a <code>separator</code> focusable to create a <rref>widget</rref> that both provides a visible boundary between two sections of content and enables the user to change the relative size of the sections by changing the position of the <code>separator</code>. A variable <code>separator</code> widget can be moved continuously within a range, whereas a fixed <code>separator</code> widget supports only two discrete positions. Typically, a fixed <code>separator</code> widget is used to toggle one of the sections between expanded and collapsed states. Authors MAY use <sref>aria-expanded</sref> to communicate the state of a <code>separator</code> widget.</p>
+				<p>If a <code>separator</code> widget supports continuously variable positioning within a range of positions, authors MAY use <pref>aria-valuenow</pref> to specify a proportional size for one of the sections. For example, in a book reader with a moveable <code>separator</code> dividing the window between a topic pane and a table of contents pane, the separator could be labeled &quot;Table of Contents&quot; and its value set to <code>50</code> in a range of <code>0</code> to <code>100</code> when the table of contents pane is at half its maximum size.</p>
 				<p>Elements with the role <code>separator</code> have an implicit <pref>aria-orientation</pref> value of <code>horizontal</code>.</p>
 			</div>
 			<table class="role-features">
@@ -6130,7 +6132,12 @@ <h5 id="role-presentation-ednote-none">Editorial Note regarding the ARIA 1.1 <rr
 					</tr>
 					<tr>
 						<th class="role-parent-head" scope="row">Superclass Role:</th>
-						<td class="role-parent"><rref>structure</rref></td>
+						<td class="role-parent">
+							<ul>
+								<li><rref>structure</rref></li>
+								<li>[ARIA 1.1] <rref>widget</rref>
+							</ul>
+						</td>
 					</tr>
 					<tr>
 						<th class="role-children-head" scope="row">Subclass Roles:</th>
@@ -6160,8 +6167,16 @@ <h5 id="role-presentation-ednote-none">Editorial Note regarding the ARIA 1.1 <rr
 						<th class="role-properties-head" scope="row">Supported States and Properties:</th>
 						<td class="role-properties">
 							<ul>
-								<li><sref>aria-expanded</sref></li>
 								<li><pref>aria-orientation</pref></li>
+								<li>If the separator is focusable, then it also supports:
+									<ul>
+										<li><sref>aria-expanded</sref></li>
+										<li>[ARIA 1.1] <pref>aria-valuemax</pref></li>
+										<li>[ARIA 1.1] <pref>aria-valuemin</pref></li>
+										<li>[ARIA 1.1] <pref>aria-valuenow</pref></li>
+										<li>[ARIA 1.1] <pref>aria-valuetext</pref></li>
+									</ul>
+								</li>
 							</ul>
 						</td>
 					</tr>
@@ -11087,6 +11102,7 @@ <h2>Substantive changes since the <a href="http://www.w3.org/TR/2015/WD-wai-aria
 			<li>27-May-2016: Remove <code>text</code>. The ARIA Working Group agreed to <a href="https://lists.w3.org/Archives/Public/public-aria-admin/2016Apr/0030.html">move the text role to ARIA 2.0</a>. Note that the content is currently only commented out until we branch for ARIA 1.1.</li>
 			<li>02-Jun-2016: Add children-presentational <code>true</code> to <rref>checkbox</rref>, <rref>menuitem</rref>, <rref>menuitemcheckbox</rref>, <rref>menuitemradio</rref>, <rref>option</rref>, <rref>radio</rref>, <rref>spinbutton</rref>, <rref>switch</rref>, <rref>tab</rref>, and <rref>treeitem</rref>. (N.B. See subsequent items as some of this is being undone as the result of further discussions within the working group.)</li>
 			<li>23-Jun-2016: Remove children-presentational <code>true</code> from <rref>spinbutton</rref>; make <rref>spinbutton</rref> a subclass of <rref>composite</rref>.</li>
+			<li>24-Jun-2016: Add <rref>widget</rref> as a (possible) superclass of <rref>separator</rref>. Add <pref>aria-valuemax</pref>, <pref>aria-valuemin</pref>, <pref>aria-valuenow</pref>, and <pref>aria-valuetext</pref> as supported properties of <rref>separator</rref>.</li>
 		</ul>
 	</section>
 	<section>