Bug 879570 - Add mouse scroll support to start page r=mbrubeck

--HG--
extra : rebase_source : 7327481bec62faa7d106bab8685b30b317658fb6

browser/metro/base/content/browser-ui.js

@@ -1409,6 +1409,7 @@ var StartUI = {
     Elements.startUI.addEventListener("autocompleteend", this, false);
     Elements.startUI.addEventListener("contextmenu", this, false);
     Elements.startUI.addEventListener("click", this, false);
+    Elements.startUI.addEventListener("MozMousePixelScroll", this, false);
 
     this.sections.forEach(function (sectionName) {
       let section = window[sectionName];
@@ -1512,6 +1513,16 @@ var StartUI = {
       case "click":
         this.onClick(aEvent);
         break;
+
+      case "MozMousePixelScroll":
+        let startBox = document.getElementById("start-scrollbox");
+        let [, scrollInterface] = ScrollUtils.getScrollboxFromElement(startBox);
+
+        scrollInterface.scrollBy(aEvent.detail, 0);
+
+        aEvent.preventDefault();
+        aEvent.stopPropagation();
+        break;
     }
   }
 };