diff --git a/lib/OpenLayers/Events.js b/lib/OpenLayers/Events.js
index 2de1165a83..04b90f2bdb 100644
--- a/lib/OpenLayers/Events.js
+++ b/lib/OpenLayers/Events.js
@@ -452,7 +452,9 @@ OpenLayers.Events = OpenLayers.Class({
     /**
      * APIProperty: extensions
      * {Object} Event extensions registered with this instance. Keys are
-     *     event types, values are <OpenLayers.Events.*> extension instances.
+     *     event types, values are {OpenLayers.Events.*} extension instances or
+     *     {Boolean} for events that an instantiated extension provides in
+     *     addition to the one it was created for.
      *
      * Extensions create an event in addition to browser events, which usually
      * fires when a sequence of browser events is completed. Extensions are
@@ -462,9 +464,9 @@ OpenLayers.Events = OpenLayers.Class({
      * Extensions are created in the <OpenLayers.Events> namespace using
      * <OpenLayers.Class>, and named after the event they provide.
      * The constructor receives the target <OpenLayers.Events> instance as
-     * argument. Extensions should register their browser events using
-     * <register>, with {extension: true} as 4th argument. See below for a
-     * minimal extension.
+     * argument. Extensions that need to capture browser events before they
+     * propagate can register their listeners events using <register>, with
+     * {extension: true} as 4th argument.
      *
      * If an extension creates more than one event, an alias for each event
      * type should be created and reference the same class. The constructor
@@ -480,11 +482,14 @@ OpenLayers.Events = OpenLayers.Class({
      *           this.target = target;
      *           this.target.register("click", this, this.doStuff, {extension: true});
      *           // only required if extension provides more than one event type
-     *           this.target.extensions["foostart"] = this;
-     *           this.target.extensions["fooend"] = this;
+     *           this.target.extensions["foostart"] = true;
+     *           this.target.extensions["fooend"] = true;
      *       },
      *       destroy: function() {
      *           this.target.unregister("click", this, this.doStuff);
+     *           // only required if extension provides more than one event type
+     *           delete this.target.extensions["foostart"];
+     *           delete this.target.extensions["fooend"];
      *       },
      *       doStuff: function(evt) {
      *           var propagate = true;
@@ -565,7 +570,9 @@ OpenLayers.Events = OpenLayers.Class({
      */
     destroy: function () {
         for (var e in this.extensions) {
-            this.extensions[e].destroy();
+            if (typeof this.extensions[e] !== "boolean") {
+                this.extensions[e].destroy();
+            }
         }
         this.extensions = null;
         if (this.element) {