diff --git a/core/blockly.js b/core/blockly.js
index 8b7083401..1e832ac16 100644
--- a/core/blockly.js
+++ b/core/blockly.js
@@ -402,11 +402,15 @@ Blockly.defineBlocksWithJsonArray = function(jsonArray) {
  * @param {boolean} opt_noCaptureIdentifier True if triggering on this event
  *     should not block execution of other event handlers on this touch or other
  *     simultaneous touches.
+ * @param {boolean} opt_noPreventDefault True if triggering on this event
+ *     should prevent the default handler.  False by default.  If
+ *     opt_noPreventDefault is provided, opt_noCaptureIdentifier must also be
+ *     provided.
  * @return {!Array.<!Array>} Opaque data that can be passed to unbindEvent_.
  * @private
  */
 Blockly.bindEventWithChecks_ = function(node, name, thisObject, func,
-    opt_noCaptureIdentifier) {
+    opt_noCaptureIdentifier, opt_noPreventDefault) {
   var handled = false;
   var wrapFunc = function(e) {
     var captureIdentifier = !opt_noCaptureIdentifier;
@@ -434,8 +438,10 @@ Blockly.bindEventWithChecks_ = function(node, name, thisObject, func,
   if (name in Blockly.Touch.TOUCH_MAP) {
     var touchWrapFunc = function(e) {
       wrapFunc(e);
-      // Stop the browser from scrolling/zooming the page.
-      if (handled) {
+      // Calling preventDefault stops the browser from scrolling/zooming the
+      // page.
+      var preventDef = !opt_noPreventDefault;
+      if (handled && preventDef) {
         e.preventDefault();
       }
     };
diff --git a/core/toolbox.js b/core/toolbox.js
index 6d72c154f..40378e101 100644
--- a/core/toolbox.js
+++ b/core/toolbox.js
@@ -170,7 +170,7 @@ Blockly.Toolbox.prototype.init = function() {
           Blockly.hideChaff(true);
         }
         Blockly.Touch.clearTouchIdentifier();  // Don't block future drags.
-      });
+      }, /*opt_noCaptureIdentifier*/ false, /*opt_noPreventDefault*/ true);
   var workspaceOptions = {
     disabledPatternId: workspace.options.disabledPatternId,
     parentWorkspace: workspace,
@@ -511,7 +511,7 @@ Blockly.Toolbox.TreeControl.prototype.enterDocument = function() {
   // Add touch handler.
   if (goog.events.BrowserFeature.TOUCH_ENABLED) {
     var el = this.getElement();
-    Blockly.bindEventWithChecks_(el, goog.events.EventType.TOUCHSTART, this,
+    Blockly.bindEventWithChecks_(el, goog.events.EventType.TOUCHEND, this,
         this.handleTouchEvent_);
   }
 };
@@ -522,13 +522,12 @@ Blockly.Toolbox.TreeControl.prototype.enterDocument = function() {
  * @private
  */
 Blockly.Toolbox.TreeControl.prototype.handleTouchEvent_ = function(e) {
-  e.preventDefault();
   var node = this.getNodeFromEvent_(e);
-  if (node && e.type === goog.events.EventType.TOUCHSTART) {
+  if (node && e.type === goog.events.EventType.TOUCHEND) {
     // Fire asynchronously since onMouseDown takes long enough that the browser
     // would fire the default mouse event before this method returns.
     setTimeout(function() {
-      node.onMouseDown(e);  // Same behaviour for click and touch.
+      node.onClick_(e);  // Same behaviour for click and touch.
     }, 1);
   }
 };
@@ -630,7 +629,7 @@ Blockly.Toolbox.TreeNode.prototype.getExpandIconSafeHtml = function() {
  * @param {!goog.events.BrowserEvent} e The browser event.
  * @override
  */
-Blockly.Toolbox.TreeNode.prototype.onMouseDown = function(e) {
+Blockly.Toolbox.TreeNode.prototype.onClick_ = function(e) {
   // Expand icon.
   if (this.hasChildren() && this.isUserCollapsible_) {
     this.toggle();
@@ -643,6 +642,16 @@ Blockly.Toolbox.TreeNode.prototype.onMouseDown = function(e) {
   this.updateRow();
 };
 
+/**
+ * Suppress the inherited mouse down behaviour.
+ * @param {!goog.events.BrowserEvent} e The browser event.
+ * @override
+ * @private
+ */
+Blockly.Toolbox.TreeNode.prototype.onMouseDown = function(e) {
+  // NOPE.
+};
+
 /**
  * Suppress the inherited double-click behaviour.
  * @param {!goog.events.BrowserEvent} e The browser event.