Print Preview: Improving accessibility of margins UI.

chrome/browser/resources/print_preview/margin_textbox.js

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 cr.define('print_preview', function() {
   'strict';
 
   function MarginTextbox(groupName) {
     var box = document.createElement('input');
     box.__proto__ = MarginTextbox.prototype;
@@ skipping 115 matching lines @@
 
     /**
      * Adds event listeners for various events.
      * @private
      */
     addEventListeners_: function() {
       this.oninput = this.resetTimer_.bind(this);
       this.onblur = this.onBlur_.bind(this);
       this.onkeypress = this.onKeyPressed_.bind(this);
       this.onkeyup = this.onKeyUp_.bind(this);
+      this.onfocus = function() {
+        cr.dispatchSimpleEvent(document, 'marginTextboxFocused');
+      };
     },
 
     /**
      * Executes whenever a blur event occurs.
      * @private
      */
     onBlur_: function() {
       clearTimeout(this.timerId_);
       this.validate();
       if (!this.isValid) {
@@ skipping 60 matching lines @@
         return;
       cr.dispatchSimpleEvent(this, 'MarginsMayHaveChanged');
     }
 
   };
 
   return {
     MarginTextbox: MarginTextbox
   };
 });