diff --git a/core/events.js b/core/events.js
index 39a768074..be0612c66 100644
--- a/core/events.js
+++ b/core/events.js
@@ -249,12 +249,11 @@ Blockly.Events.filter = function(queueIn, forward) {
           (lastEvent.element == 'commentOpen' ||
            lastEvent.element == 'mutatorOpen' ||
            lastEvent.element == 'warningOpen')) {
-        // Merge click events.
-        lastEvent.newValue = event.newValue;
+        // Drop click events caused by opening/closing bubbles.
       } else {
         // Collision: newer events should merge into this event to maintain
         // order.
-        hash[key] = { event: event, index: 1};
+        hash[key] = {event: event, index: 1};
         mergedQueue.push(event);
       }
     }
diff --git a/core/ui_events.js b/core/ui_events.js
index d3ec6d6da..61b169bba 100644
--- a/core/ui_events.js
+++ b/core/ui_events.js
@@ -37,7 +37,7 @@ goog.require('Blockly.Events.Abstract');
  * categories).
  * UI events do not undo or redo.
  * @param {Blockly.Block} block The affected block.
- * @param {string} element One of 'selected', 'comment', 'mutator', etc.
+ * @param {string} element One of 'selected', 'comment', 'mutatorOpen', etc.
  * @param {*} oldValue Previous value of element.
  * @param {*} newValue New value of element.
  * @extends {Blockly.Events.Abstract}