add visibility functions to popup

git-svn-id: http://svn.openlayers.org/trunk/openlayers@412 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Popup.js

@@ -122,6 +122,35 @@ OpenLayers.Popup.prototype = {
         }
     },
 
+    /**
+     * @returns Boolean indicating whether or not the popup is visible
+     * @type Boolean
+     */
+    visible: function() {
+        return Element.visible(this.div);
+    },
+
+    /**
+     * 
+     */
+    toggle: function() {
+        Element.toggle(this.div);
+    }
+
+    /**
+     *
+     */
+    show: function() {
+        Element.show(this.div);
+    },
+
+    /**
+     *
+     */
+    hide: function() {
+        Element.hide(this.div);
+    },
+
     /**
     * @param {OpenLayers.Size} size
     */