diff --git a/core/blockly.js b/core/blockly.js
index 85d311e6d..365255099 100644
--- a/core/blockly.js
+++ b/core/blockly.js
@@ -222,7 +222,8 @@ Blockly.onMouseMove_ = function(e) {
  * @private
  */
 Blockly.onKeyDown_ = function(e) {
-  if (Blockly.isTargetInput_(e)) {
+  if (Blockly.mainWorkspace.options.readOnly || Blockly.isTargetInput_(e)) {
+    // No key actions on readonly workspaces.
     // When focused on an HTML text input widget, don't trap any keys.
     return;
   }
diff --git a/core/events.js b/core/events.js
index 8aafdfdb1..f890d85cb 100644
--- a/core/events.js
+++ b/core/events.js
@@ -239,6 +239,37 @@ Blockly.Events.getDescendantIds_ = function(block) {
   return ids;
 };
 
+/**
+ * Decode the JSON into an event.
+ * @param {!Object} json JSON representation.
+ * @param {!Blockly.Workspace} workspace Target workspace for event.
+ */
+Blockly.Events.fromJson = function(json, workspace) {
+  var event;
+  switch (json.type) {
+    case Blockly.Events.CREATE:
+      event = new Blockly.Events.Create(null);
+      break;
+    case Blockly.Events.DELETE:
+      event = new Blockly.Events.Delete(null);
+      break;
+    case Blockly.Events.CHANGE:
+      event = new Blockly.Events.Change(null);
+      break;
+    case Blockly.Events.MOVE:
+      event = new Blockly.Events.Move(null);
+      break;
+    case Blockly.Events.UI:
+      event = new Blockly.Events.Ui(null);
+      break;
+    default:
+      throw 'Unknown event type.'
+  }
+  event.fromJson(json);
+  event.workspaceId = workspace.id;
+  return event;
+};
+
 /**
  * Abstract class for an event.
  * @param {Blockly.Block} block The block.
@@ -260,8 +291,7 @@ Blockly.Events.Abstract = function(block) {
 Blockly.Events.Abstract.prototype.toJson = function() {
   var json = {
     'type': this.type,
-    'blockId': this.blockId,
-    'workspaceId': this.workspaceId
+    'blockId': this.blockId
   };
   if (this.group) {
     json['group'] = this.group;
@@ -269,6 +299,15 @@ Blockly.Events.Abstract.prototype.toJson = function() {
   return json;
 };
 
+/**
+ * Decode the JSON event.
+ * @param {!Object} json JSON representation.
+ */
+Blockly.Events.Abstract.prototype.fromJson = function(json) {
+  this.blockId = json['blockId'];
+  this.group = json['group'];
+};
+
 /**
  * Does this event record any change of state?
  * @return {boolean} True if null, false if something changed.
@@ -287,11 +326,14 @@ Blockly.Events.Abstract.prototype.run = function(forward) {
 
 /**
  * Class for a block creation event.
- * @param {!Blockly.Block} block The created block.
+ * @param {Blockly.Block} block The created block.  Null for a blank event.
  * @extends {Blockly.Events.Abstract}
  * @constructor
  */
 Blockly.Events.Create = function(block) {
+  if (!block) {
+    return;  // Blank event to be populated by fromJson.
+  }
   Blockly.Events.Create.superClass_.constructor.call(this, block);
   this.xml = Blockly.Xml.blockToDomWithXY(block);
   this.ids = Blockly.Events.getDescendantIds_(block);
@@ -315,13 +357,23 @@ Blockly.Events.Create.prototype.toJson = function() {
   return json;
 };
 
+/**
+ * Decode the JSON event.
+ * @param {!Object} json JSON representation.
+ */
+Blockly.Events.Create.prototype.fromJson = function(json) {
+  Blockly.Events.Create.superClass_.fromJson.call(this, json);
+  this.xml = Blockly.Xml.textToDom('<xml>' + json['xml'] + '</xml>').firstChild;
+  this.ids = json['ids'];
+};
+
 /**
  * Run a creation event.
  * @param {boolean} forward True if run forward, false if run backward (undo).
  */
 Blockly.Events.Create.prototype.run = function(forward) {
+  var workspace = Blockly.Workspace.getById(this.workspaceId);
   if (forward) {
-    var workspace = Blockly.Workspace.getById(this.workspaceId);
     var xml = goog.dom.createDom('xml');
     xml.appendChild(this.xml);
     Blockly.Xml.domToWorkspace(xml, workspace);
@@ -340,11 +392,14 @@ Blockly.Events.Create.prototype.run = function(forward) {
 
 /**
  * Class for a block deletion event.
- * @param {!Blockly.Block} block The deleted block.
+ * @param {Blockly.Block} block The deleted block.  Null for a blank event.
  * @extends {Blockly.Events.Abstract}
  * @constructor
  */
 Blockly.Events.Delete = function(block) {
+  if (!block) {
+    return;  // Blank event to be populated by fromJson.
+  }
   if (block.getParent()) {
     throw 'Connected blocks cannot be deleted.';
   }
@@ -370,6 +425,15 @@ Blockly.Events.Delete.prototype.toJson = function() {
   return json;
 };
 
+/**
+ * Decode the JSON event.
+ * @param {!Object} json JSON representation.
+ */
+Blockly.Events.Delete.prototype.fromJson = function(json) {
+  Blockly.Events.Delete.superClass_.fromJson.call(this, json);
+  this.ids = json['ids'];
+};
+
 /**
  * Run a deletion event.
  * @param {boolean} forward True if run forward, false if run backward (undo).
@@ -395,7 +459,7 @@ Blockly.Events.Delete.prototype.run = function(forward) {
 
 /**
  * Class for a block change event.
- * @param {!Blockly.Block} block The changed block.
+ * @param {Blockly.Block} block The changed block.  Null for a blank event.
  * @param {string} element One of 'field', 'comment', 'disabled', etc.
  * @param {?string} name Name of input or field affected, or null.
  * @param {string} oldValue Previous value of element.
@@ -404,6 +468,9 @@ Blockly.Events.Delete.prototype.run = function(forward) {
  * @constructor
  */
 Blockly.Events.Change = function(block, element, name, oldValue, newValue) {
+  if (!block) {
+    return;  // Blank event to be populated by fromJson.
+  }
   Blockly.Events.Change.superClass_.constructor.call(this, block);
   this.element = element;
   this.name = name;
@@ -432,6 +499,17 @@ Blockly.Events.Change.prototype.toJson = function() {
   return json;
 };
 
+/**
+ * Decode the JSON event.
+ * @param {!Object} json JSON representation.
+ */
+Blockly.Events.Change.prototype.fromJson = function(json) {
+  Blockly.Events.Change.superClass_.fromJson.call(this, json);
+  this.element = json['element'];
+  this.name = json['name'];
+  this.newValue = json['newValue'];
+};
+
 /**
  * Does this event record any change of state?
  * @return {boolean} True if something changed.
@@ -498,11 +576,14 @@ Blockly.Events.Change.prototype.run = function(forward) {
 
 /**
  * Class for a block move event.  Created before the move.
- * @param {!Blockly.Block} block The moved block.
+ * @param {Blockly.Block} block The moved block.  Null for a blank event.
  * @extends {Blockly.Events.Abstract}
  * @constructor
  */
 Blockly.Events.Move = function(block) {
+  if (!block) {
+    return;  // Blank event to be populated by fromJson.
+  }
   Blockly.Events.Move.superClass_.constructor.call(this, block);
   var location = this.currentLocation_();
   this.oldParentId = location.parentId;
@@ -536,6 +617,21 @@ Blockly.Events.Move.prototype.toJson = function() {
   return json;
 };
 
+/**
+ * Decode the JSON event.
+ * @param {!Object} json JSON representation.
+ */
+Blockly.Events.Move.prototype.fromJson = function(json) {
+  Blockly.Events.Move.superClass_.fromJson.call(this, json);
+  this.newParentId = json['newParentId'];
+  this.newInputName = json['newInputName'];
+  if (json['newCoordinate']) {
+    var xy = json['newCoordinate'].split(',');
+    this.newCoordinate =
+        new goog.math.Coordinate(parseFloat(xy[0]), parseFloat(xy[1]));
+  }
+};
+
 /**
  * Record the block's new location.  Called after the move.
  */
@@ -662,3 +758,13 @@ Blockly.Events.Ui.prototype.toJson = function() {
   }
   return json;
 };
+
+/**
+ * Decode the JSON event.
+ * @param {!Object} json JSON representation.
+ */
+Blockly.Events.Ui.prototype.fromJson = function(json) {
+  Blockly.Events.Ui.superClass_.fromJson.call(this, json);
+  this.element = json['element'];
+  this.newValue = json['newValue'];
+};
diff --git a/demos/index.html b/demos/index.html
index 3fe46a780..f9f9833e7 100644
--- a/demos/index.html
+++ b/demos/index.html
@@ -160,6 +160,18 @@
       </td>
     </tr>
 
+    <tr>
+      <td>
+        <a href="mirror/index.html">
+          <img src="mirror/icon.png" height=80 width=100>
+        </a>
+      </td>
+      <td>
+        <div><a href="mirror/index.html">Mirrored Blockly</a></div>
+        <div>Two Blockly instances connected as master-slave.</div>
+      </td>
+    </tr>
+
     <tr>
       <td>
         <a href="code/index.html">
diff --git a/demos/mirror/icon.png b/demos/mirror/icon.png
new file mode 100644
index 000000000..45e2a9a29
Binary files /dev/null and b/demos/mirror/icon.png differ
diff --git a/demos/mirror/index.html b/demos/mirror/index.html
new file mode 100644
index 000000000..8721d7354
--- /dev/null
+++ b/demos/mirror/index.html
@@ -0,0 +1,76 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Blockly Demo: Mirrored Blockly</title>
+  <script src="../../blockly_compressed.js"></script>
+  <script src="../../blocks_compressed.js"></script>
+  <script src="../../msg/js/en.js"></script>
+  <style>
+    body {
+      background-color: #fff;
+      font-family: sans-serif;
+    }
+    h1 {
+      font-weight: normal;
+      font-size: 140%;
+    }
+  </style>
+</head>
+<body>
+  <h1><a href="https://developers.google.com/blockly/">Blockly</a> &gt;
+    <a href="../index.html">Demos</a> &gt; Mirrored Blockly</h1>
+
+  <p>This is a simple demo of a master Blockly that controls a slave Blockly.
+  Open the JavaScript console to see the event passing.</p>
+
+  <p>&rarr; More info on <a href="https://developers.google.com/blockly/hacking/events">events</a>&hellip;</p>
+
+  <table width="100%">
+    <tr>
+      <td>
+        <div id="masterDiv" style="height: 480px; width: 600px;"></div>
+      </td>
+      <td>
+        <div id="slaveDiv" style="height: 480px; width: 430px;"></div>
+      </td>
+    </tr>
+  </table>
+
+  <xml id="toolbox" style="display: none">
+    <block type="controls_if"></block>
+    <block type="logic_compare"></block>
+    <block type="controls_repeat_ext"></block>
+    <block type="math_number"></block>
+    <block type="math_arithmetic"></block>
+    <block type="text"></block>
+    <block type="text_print"></block>
+  </xml>
+
+  <script>
+    // Inject master workspace.
+    var masterWorkspace = Blockly.inject('masterDiv',
+        {media: '../../media/',
+         toolbox: document.getElementById('toolbox')});
+    // Inject slave workspace.
+    var slaveWorkspace = Blockly.inject('slaveDiv',
+        {media: '../../media/',
+         readOnly: true});
+    // Listen to events on master workspace.
+    masterWorkspace.addChangeListener(mirrorEvent);
+
+    function mirrorEvent(masterEvent) {
+      if (masterEvent.type == Blockly.Events.UI) {
+        return;  // Don't mirror UI events.
+      }
+      // Convert event to JSON.  This could then be transmitted across the net.
+      var json = masterEvent.toJson();
+      console.log(json);
+      // Convert JSON back into an event, then execute it.
+      var slaveEvent = Blockly.Events.fromJson(json, slaveWorkspace);
+      slaveEvent.run(true);
+    }
+  </script>
+
+</body>
+</html>