Fix touch delay on dropdowns (Issue 247).

git-svn-id: http://blockly.googlecode.com/svn/trunk@1765 c400ca83-b69d-9dd7-9705-49c6b8615e23

core/field_dropdown.js

@@ -127,7 +127,24 @@ Blockly.FieldDropdown.prototype.showEditor_ = function() {
     menu.addChild(menuItem, true);
     menuItem.setChecked(value == this.value_);
   }
+  // Listen for mouse/keyboard events.
   goog.events.listen(menu, goog.ui.Component.EventType.ACTION, callback);
+  // Listen for touch events (why doesn't Closure handle this already?).
+  function callbackTouchStart(e) {
+    var control = this.getOwnerControl(/** @type {Node} */ (e.target));
+    // Highlight the menu item.
+    control.handleMouseDown(e);
+  }
+  function callbackTouchEnd(e) {
+    var control = this.getOwnerControl(/** @type {Node} */ (e.target));
+    // Activate the menu item.
+    control.performActionInternal(e);
+  }
+  menu.getHandler().listen(menu.getElement(), goog.events.EventType.TOUCHSTART,
+                           callbackTouchStart);
+  menu.getHandler().listen(menu.getElement(), goog.events.EventType.TOUCHEND,
+                           callbackTouchEnd);
+
   // Record windowSize and scrollOffset before adding menu.
   var windowSize = goog.dom.getViewportSize();
   var scrollOffset = goog.style.getViewportPageOffset(document);