diff --git a/browser/metro/base/content/helperui/ChromeSelectionHandler.js b/browser/metro/base/content/helperui/ChromeSelectionHandler.js
index af458b07013..2c2ba95a405 100644
--- a/browser/metro/base/content/helperui/ChromeSelectionHandler.js
+++ b/browser/metro/base/content/helperui/ChromeSelectionHandler.js
@@ -8,11 +8,8 @@
 
 let Ci = Components.interfaces;
 
-const kCaretMode = 1;
-const kSelectionMode = 2;
-
 var ChromeSelectionHandler = {
-  _mode: kSelectionMode,
+  _mode: this._SELECTION_MODE,
 
   /*************************************************
    * Messaging wrapper
@@ -33,6 +30,10 @@ var ChromeSelectionHandler = {
    * General selection start method for both caret and selection mode.
    */
   _onSelectionAttach: function _onSelectionAttach(aJson) {
+    // Clear previous ChromeSelectionHandler state.
+    this._deactivate();
+
+    // Initialize ChromeSelectionHandler state.
     this._domWinUtils = Util.getWindowUtils(window);
     this._contentWindow = window;
     this._targetElement = aJson.target;
@@ -54,11 +55,14 @@ var ChromeSelectionHandler = {
       return;
     }
 
+    // Add a listener to respond to programmatic selection changes.
+    selection.QueryInterface(Ci.nsISelectionPrivate).addSelectionListener(this);
+
     if (!selection.isCollapsed) {
-      this._mode = kSelectionMode;
+      this._mode = this._SELECTION_MODE;
       this._updateSelectionUI("start", true, true);
     } else {
-      this._mode = kCaretMode;
+      this._mode = this._CARET_MODE;
       this._updateSelectionUI("caret", false, false, true);
     }
 
@@ -156,9 +160,9 @@ var ChromeSelectionHandler = {
       return;
     }
     this._updateSelectionUI("update",
-                            this._mode == kSelectionMode,
-                            this._mode == kSelectionMode,
-                            this._mode == kCaretMode);
+                            this._mode == this._SELECTION_MODE,
+                            this._mode == this._SELECTION_MODE,
+                            this._mode == this._CARET_MODE);
   },
 
   /*
@@ -188,7 +192,7 @@ var ChromeSelectionHandler = {
 
     // We bail if things get out of sync here implying we missed a message.
     this._selectionMoveActive = true;
-    this._mode = kSelectionMode;
+    this._mode = this._SELECTION_MODE;
 
     // Update the position of the selection marker that is *not*
     // being dragged.
@@ -266,7 +270,7 @@ var ChromeSelectionHandler = {
   /*
    * _clearSelection
    *
-   * Clear existing selection if it exists and reset our internla state.
+   * Clear existing selection if it exists and reset our internal state.
    */
   _clearSelection: function _clearSelection() {
     let selection = this._getSelection();
@@ -278,9 +282,30 @@ var ChromeSelectionHandler = {
   /*
    * _closeSelection
    *
-   * Shuts SelectionHandler down.
+   * Shuts ChromeSelectionHandler and SelectionHelperUI down.
    */
   _closeSelection: function _closeSelection() {
+    this._deactivate();
+    this.sendAsync("Content:HandlerShutdown", {});
+  },
+
+  /*
+   * _deactivate
+   *
+   * Resets ChromeSelectionHandler state, previously initialized in
+   * general selection start-method |_onSelectionAttach()|.
+   */
+  _deactivate: function _deactivate() {
+    // Remove our selection notification listener.
+    let selection = this._getSelection();
+    if (selection) {
+      try {
+        selection.QueryInterface(Ci.nsISelectionPrivate).removeSelectionListener(this);
+      } catch(e) {
+        // Fail safe during multiple _deactivate() calls.
+      }
+    }
+
     this._clearTimers();
     this._cache = null;
     this._contentWindow = null;
@@ -291,7 +316,7 @@ var ChromeSelectionHandler = {
     this._selectionMoveActive = false;
     this._domWinUtils = null;
     this._targetIsEditable = false;
-    this.sendAsync("Content:HandlerShutdown", {});
+    this._mode = null;
   },
 
   get hasSelection() {
diff --git a/browser/metro/base/content/library/SelectionPrototype.js b/browser/metro/base/content/library/SelectionPrototype.js
index 9ba512c95b9..0407be612a0 100644
--- a/browser/metro/base/content/library/SelectionPrototype.js
+++ b/browser/metro/base/content/library/SelectionPrototype.js
@@ -53,6 +53,9 @@ dump("### SelectionPrototype.js loaded\n");
 var SelectionPrototype = function() { }
 
 SelectionPrototype.prototype = {
+  _CARET_MODE: 1, // Single monocle mode (Collapsed caret).
+  _SELECTION_MODE: 2, // Double monocle mode (Selection w/Text).
+
   _debugEvents: false,
   _cache: {},
   _targetElement: null,
@@ -169,6 +172,28 @@ SelectionPrototype.prototype = {
     this._debugEvents = aMsg.dumpEvents;
   },
 
+  /*
+   * Selection Changed notification listener. This allows us to respond to selection changes
+   * introduced programmatically by Gecko events, target-page support code, etc.
+   */
+  notifySelectionChanged: function notifySelectionChanged(aDocument, aSelection, aReason) {
+    // Ignore user generated selectionChange notifications during monocle/marker movement.
+    if ((typeof SelectionHelperUI != "undefined") && SelectionHelperUI.hasActiveDrag) {
+      return;
+    }
+
+    // Ignore selectionChange notifications, unless reason is mouseup, or unknown.
+    if (!(aReason & Ci.nsISelectionListener.MOUSEUP_REASON) &&
+        (aReason != Ci.nsISelectionListener.NO_REASON)) {
+      return;
+    }
+
+    // If in selection mode, and we have a selection, update it.
+    if (this._mode == this._SELECTION_MODE && !aSelection.isCollapsed) {
+      this._updateSelectionUI("update", true, true);
+    }
+  },
+
   /*************************************************
    * Selection api
    */
diff --git a/browser/metro/base/tests/mochitest/browser_selection_urlbar.js b/browser/metro/base/tests/mochitest/browser_selection_urlbar.js
index 647f8e7833f..c9322eb0cf2 100644
--- a/browser/metro/base/tests/mochitest/browser_selection_urlbar.js
+++ b/browser/metro/base/tests/mochitest/browser_selection_urlbar.js
@@ -232,7 +232,7 @@ gTests.push({
 
 gTests.push({
   desc: "Bug 957646 - Selection monocles sometimes don't display when tapping" +
-        " text ion the nav bar.",
+        " text in the nav bar.",
   run: function() {
     yield showNavBar();
 
@@ -250,6 +250,43 @@ gTests.push({
   }
 });
 
+gTests.push({
+  desc: "Bug 972574 - Monocles not matching selection after double tap" +
+        " in URL text field.",
+  run: function() {
+    yield showNavBar();
+
+    let MARGIN_OF_ERROR = 15;
+    let EST_URLTEXT_WIDTH = 125;
+
+    let edit = document.getElementById("urlbar-edit");
+    edit.value = "http://www.wikipedia.org/";
+
+    // Determine a tap point centered on URL.
+    let editRectangle = edit.getBoundingClientRect();
+    let midX = editRectangle.left + Math.ceil(EST_URLTEXT_WIDTH / 2);
+    let midY = editRectangle.top + Math.ceil(editRectangle.height / 2);
+
+    // Tap inside the input for fluffing to take effect.
+    sendTap(window, midX, midY);
+
+    // Double-tap inside the input to selectALL.
+    sendDoubleTap(window, midX, midY);
+
+    // Check for start/end monocles positioned within accepted margins.
+    checkMonoclePositionRange("start",
+      Math.ceil(editRectangle.left - MARGIN_OF_ERROR),
+      Math.ceil(editRectangle.left + MARGIN_OF_ERROR),
+      Math.ceil(editRectangle.top + editRectangle.height - MARGIN_OF_ERROR),
+      Math.ceil(editRectangle.top + editRectangle.height + MARGIN_OF_ERROR));
+    checkMonoclePositionRange("end",
+      Math.ceil(editRectangle.left + EST_URLTEXT_WIDTH - MARGIN_OF_ERROR),
+      Math.ceil(editRectangle.left + EST_URLTEXT_WIDTH + MARGIN_OF_ERROR),
+      Math.ceil(editRectangle.top + editRectangle.height - MARGIN_OF_ERROR),
+      Math.ceil(editRectangle.top + editRectangle.height + MARGIN_OF_ERROR));
+  }
+});
+
 gTests.push({
   desc: "Bug 972428 - grippers not appearing under the URL field when adding " +
         "text.",