Selectmenu: Add missing instance method

Author: jzaefferer

entries/selectmenu.xml

@@ -102,6 +102,7 @@
 		<xi:include href="../includes/widget-method-destroy.xml" xmlns:xi="http://www.w3.org/2003/XInclude"/>
 		<xi:include href="../includes/widget-method-disable.xml" xmlns:xi="http://www.w3.org/2003/XInclude"/>
 		<xi:include href="../includes/widget-method-enable.xml" xmlns:xi="http://www.w3.org/2003/XInclude"/>
+		<xi:include href="../includes/widget-method-instance.xml" xmlns:xi="http://www.w3.org/2003/XInclude"/>
 		<method name="menuWidget">
 			<desc>Returns a <code>jQuery</code> object containing the menu element.</desc>
 		</method>