Increase compatibility in addEvent

lib/scripts/compatibility.js

@@ -187,8 +187,29 @@ function prependChild(parent,element) {
 }
 
 function addEvent(element, type, handler) {
-    DEPRECATED('Use jQuery.bind() instead.');
-    jQuery(element).bind(type,{},handler);
+    DEPRECATED('Use jQuery.bind() instead. Note that jQuery’s behaviour' +
+               ' when a handler returns false differs from addEvent’s');
+    jQuery(element).bind(type,{},function (e) {
+        // returning false in an addEvent event handler did not prevent
+        // bubbling but just canceled handlers on this node and prevented
+        // default behavior, so wrap the handler call and mimic that behavior.
+        //
+        // Refer to jQuery.event.handle().
+        var ret = handler.apply(this, Array.prototype.slice.call(arguments, 0));
+        if (typeof ret !== 'undefined') {
+            if ( ret !== false ) {
+                return ret;
+            }
+            // What jQuery does.
+            e.result = ret;
+            e.preventDefault();
+            // Not what jQuery does. This would be: event.stopPropagation();
+            // Hack it so that immediate propagation (other event handlers on
+            // this element) appears stopped without stopping the actual
+            // propagation (bubbling)
+            e.isImmediatePropagationStopped = function () { return true; };
+        }
+    });
 }
 
 function removeEvent(element, type, handler) {