diff --git a/browser/base/content/browser-appmenu.inc b/browser/base/content/browser-appmenu.inc
index 9f3c750c25d9..244679d11dac 100644
--- a/browser/base/content/browser-appmenu.inc
+++ b/browser/base/content/browser-appmenu.inc
@@ -187,7 +187,6 @@
                     command="Tools:Scratchpad"/>
           <menuitem id="appmenu_styleeditor"
                     hidden="true"
-                    type="checkbox"
                     label="&styleeditor.label;"
                     key="key_styleeditor"
                     command="Tools:StyleEditor"/>
diff --git a/browser/base/content/browser-menubar.inc b/browser/base/content/browser-menubar.inc
index 1c9b34b93285..e31f98b86b9f 100644
--- a/browser/base/content/browser-menubar.inc
+++ b/browser/base/content/browser-menubar.inc
@@ -563,7 +563,6 @@
                             key="key_scratchpad"
                             command="Tools:Scratchpad"/>
                   <menuitem id="menu_styleeditor"
-                            type="checkbox"
                             hidden="true"
                             label="&styleeditor.label;"
                             accesskey="&styleeditor.accesskey;"
diff --git a/browser/base/content/browser-sets.inc b/browser/base/content/browser-sets.inc
index d5aa51544952..15e7469f809d 100644
--- a/browser/base/content/browser-sets.inc
+++ b/browser/base/content/browser-sets.inc
@@ -95,7 +95,7 @@
     <command id="Tools:RemoteDebugger" oncommand="DebuggerUI.toggleRemoteDebugger();" disabled="true"/>
     <command id="Tools:ChromeDebugger" oncommand="DebuggerUI.toggleChromeDebugger();" disabled="true"/>
     <command id="Tools:Scratchpad" oncommand="Scratchpad.openScratchpad();" disabled="true"/>
-    <command id="Tools:StyleEditor" oncommand="StyleEditor.toggle();" disabled="true"/>
+    <command id="Tools:StyleEditor" oncommand="StyleEditor.openChrome();" disabled="true"/>
     <command id="Tools:ResponsiveUI" oncommand="ResponsiveUI.toggle();" disabled="true"/>
     <command id="Tools:Addons" oncommand="BrowserOpenAddonsMgr();"/>
     <command id="Tools:Sanitize"
diff --git a/browser/base/content/browser.js b/browser/base/content/browser.js
index 120691f7c1f4..39a327513311 100644
--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -1477,7 +1477,6 @@ var gBrowserInit = {
 #ifdef MENUBAR_CAN_AUTOHIDE
       document.getElementById("appmenu_styleeditor").hidden = false;
 #endif
-      document.getElementById("developer-toolbar-styleeditor").hidden = false;
     }
 
 #ifdef MENUBAR_CAN_AUTOHIDE
@@ -1497,6 +1496,7 @@ var gBrowserInit = {
 #ifdef MENUBAR_CAN_AUTOHIDE
       document.getElementById("appmenu_responsiveUI").hidden = false;
 #endif
+      document.getElementById("developer-toolbar-responsiveui").hidden = false;
     }
 
     let appMenuButton = document.getElementById("appmenu-button");
@@ -7374,29 +7374,40 @@ var StyleEditor = {
    */
   openChrome: function SE_openChrome(aSelectedStyleSheet, aLine, aCol)
   {
-    let contentWindow = gBrowser.selectedBrowser.contentWindow;
-    let win = this.StyleEditorManager.getEditorForWindow(contentWindow);
-    if (win) {
-      this.StyleEditorManager.selectEditor(win);
-      return win;
-    } else {
-      return this.StyleEditorManager.newEditor(contentWindow,
-                                               aSelectedStyleSheet, aLine, aCol);
-    }
-  },
+    const CHROME_URL = "chrome://browser/content/styleeditor.xul";
+    const CHROME_WINDOW_TYPE = "Tools:StyleEditor";
+    const CHROME_WINDOW_FLAGS = "chrome,centerscreen,resizable,dialog=no";
 
-  toggle: function SE_toggle()
-  {
-    this.StyleEditorManager.toggleEditor(gBrowser.contentWindow);
+    // focus currently open Style Editor window for this document, if any
+    let contentWindow = gBrowser.selectedBrowser.contentWindow;
+    let contentWindowID = contentWindow.QueryInterface(Ci.nsIInterfaceRequestor).
+      getInterface(Ci.nsIDOMWindowUtils).currentInnerWindowID;
+    let enumerator = Services.wm.getEnumerator(CHROME_WINDOW_TYPE);
+    while (enumerator.hasMoreElements()) {
+      var win = enumerator.getNext();
+      if (win.styleEditorChrome.contentWindowID == contentWindowID) {
+        if (aSelectedStyleSheet) {
+          win.styleEditorChrome.selectStyleSheet(aSelectedStyleSheet, aLine, aCol);
+        }
+        win.focus();
+        return win;
+      }
+    }
+
+    let args = {
+      contentWindow: contentWindow,
+      selectedStyleSheet: aSelectedStyleSheet,
+      line: aLine,
+      col: aCol
+    };
+    args.wrappedJSObject = args;
+    let chromeWindow = Services.ww.openWindow(null, CHROME_URL, "_blank",
+                                              CHROME_WINDOW_FLAGS, args);
+    chromeWindow.focus();
+    return chromeWindow;
   }
 };
 
-XPCOMUtils.defineLazyGetter(StyleEditor, "StyleEditorManager", function() {
-  let tmp = {};
-  Cu.import("resource:///modules/devtools/StyleEditor.jsm", tmp);
-  return new tmp.StyleEditorManager(window);
-});
-
 
 XPCOMUtils.defineLazyGetter(window, "gShowPageResizers", function () {
 #ifdef XP_WIN
diff --git a/browser/base/content/browser.xul b/browser/base/content/browser.xul
index f49843ef9513..6aa60d071b95 100644
--- a/browser/base/content/browser.xul
+++ b/browser/base/content/browser.xul
@@ -1043,11 +1043,11 @@
                          class="devtools-toolbarbutton"
                          hidden="true"
                          command="Tools:Inspect"/>
-          <toolbarbutton id="developer-toolbar-styleeditor"
-                         label="&styleeditor.label;"
+          <toolbarbutton id="developer-toolbar-responsiveui"
+                         label="&responsiveDesignTool.label;"
                          class="devtools-toolbarbutton"
                          hidden="true"
-                         command="Tools:StyleEditor"/>
+                         command="Tools:ResponsiveUI"/>
           <toolbarbutton id="developer-toolbar-debugger"
                          label="&scriptsButton.label;"
                          class="devtools-toolbarbutton"
diff --git a/browser/devtools/shared/test/browser_toolbar_basic.js b/browser/devtools/shared/test/browser_toolbar_basic.js
index 31d3ae19a0d6..ba0205af0933 100644
--- a/browser/devtools/shared/test/browser_toolbar_basic.js
+++ b/browser/devtools/shared/test/browser_toolbar_basic.js
@@ -35,7 +35,6 @@ function checkOpen() {
   let close = document.getElementById("developer-toolbar-closebutton");
   let webconsole = document.getElementById("developer-toolbar-webconsole");
   let inspector = document.getElementById("developer-toolbar-inspector");
-  let styleeditor = document.getElementById("developer-toolbar-styleeditor");
   let debuggr = document.getElementById("developer-toolbar-debugger");
 
   ok(close, "Close button exists");
@@ -43,21 +42,18 @@ function checkOpen() {
   ok(!isChecked(webconsole), "web console button state 1");
   ok(!isChecked(inspector), "inspector button state 1");
   ok(!isChecked(debuggr), "debugger button state 1");
-  ok(!isChecked(styleeditor), "styleeditor button state 1");
 
   document.getElementById("Tools:WebConsole").doCommand();
 
   ok(isChecked(webconsole), "web console button state 2");
   ok(!isChecked(inspector), "inspector button state 2");
   ok(!isChecked(debuggr), "debugger button state 2");
-  ok(!isChecked(styleeditor), "styleeditor button state 2");
 
   document.getElementById("Tools:Inspect").doCommand();
 
   ok(isChecked(webconsole), "web console button state 3");
   ok(isChecked(inspector), "inspector button state 3");
   ok(!isChecked(debuggr), "debugger button state 3");
-  ok(!isChecked(styleeditor), "styleeditor button state 3");
 
   // Christmas tree!
 
@@ -70,14 +66,12 @@ function checkOpen() {
   ok(!isChecked(webconsole), "web console button state 6");
   ok(isChecked(inspector), "inspector button state 6");
   ok(!isChecked(debuggr), "debugger button state 6");
-  ok(!isChecked(styleeditor), "styleeditor button state 6");
 
   document.getElementById("Tools:Inspect").doCommand();
 
   ok(!isChecked(webconsole), "web console button state 7");
   ok(!isChecked(inspector), "inspector button state 7");
   ok(!isChecked(debuggr), "debugger button state 7");
-  ok(!isChecked(styleeditor), "styleeditor button state 7");
 
   // All closed
 
@@ -87,38 +81,9 @@ function checkOpen() {
   ok(!isChecked(webconsole), "web console button state 8");
   ok(isChecked(inspector), "inspector button state 8");
   ok(!isChecked(debuggr), "debugger button state 8");
-  ok(!isChecked(styleeditor), "styleeditor button state 8");
 
-
-  // Test Style Editor
-  document.getElementById("Tools:StyleEditor").doCommand();
-
-  ok(!isChecked(webconsole), "web console button state 9");
-  ok(isChecked(inspector), "inspector button state 9");
-  ok(!isChecked(debuggr), "debugger button state 9");
-  ok(isChecked(styleeditor), "styleeditor button state 9");
-
-  // Test Debugger
-  document.getElementById("Tools:Debugger").doCommand();
-
-  ok(!isChecked(webconsole), "web console button state 9");
-  ok(isChecked(inspector), "inspector button state 9");
-  ok(isChecked(debuggr), "debugger button state 9");
-  ok(isChecked(styleeditor), "styleeditor button state 9");
-
-  addTab("about:blank", function(browser, tab) {
-    info("Opening a new tab");
-
-    ok(!isChecked(webconsole), "web console button state 10");
-    ok(!isChecked(inspector), "inspector button state 10");
-    ok(!isChecked(debuggr), "debugger button state 10");
-    ok(!isChecked(styleeditor), "styleeditor button state 10");
-
-    gBrowser.removeCurrentTab();
-
-    oneTimeObserve(DeveloperToolbar.NOTIFICATIONS.HIDE, catchFail(checkClosed));
-    document.getElementById("Tools:DevToolbar").doCommand();
-  });
+  oneTimeObserve(DeveloperToolbar.NOTIFICATIONS.HIDE, catchFail(checkClosed));
+  document.getElementById("Tools:DevToolbar").doCommand();
 }
 
 function checkClosed() {
@@ -137,15 +102,10 @@ function checkReOpen() {
   let webconsole = document.getElementById("developer-toolbar-webconsole");
   let inspector = document.getElementById("developer-toolbar-inspector");
   let debuggr = document.getElementById("developer-toolbar-debugger");
-  let styleeditor = document.getElementById("developer-toolbar-styleeditor");
 
-  ok(isChecked(webconsole), "web console button state 99");
-  ok(isChecked(inspector), "inspector button state 99");
-  ok(isChecked(debuggr), "debugger button state 99");
-  ok(isChecked(styleeditor), "styleeditor button state 99");
-
-  // We close the style editor (not automatically closed)
-  document.getElementById("Tools:StyleEditor").doCommand();
+  ok(isChecked(webconsole), "web console button state 9");
+  ok(isChecked(inspector), "inspector button state 9");
+  ok(!isChecked(debuggr), "debugger button state 9");
 
   oneTimeObserve(DeveloperToolbar.NOTIFICATIONS.HIDE, catchFail(checkReClosed));
   document.getElementById("developer-toolbar-closebutton").doCommand();
diff --git a/browser/devtools/styleeditor/StyleEditor.jsm b/browser/devtools/styleeditor/StyleEditor.jsm
index 2f36fed169a7..1c16a38e9509 100644
--- a/browser/devtools/styleeditor/StyleEditor.jsm
+++ b/browser/devtools/styleeditor/StyleEditor.jsm
@@ -5,7 +5,7 @@
 
 "use strict";
 
-const EXPORTED_SYMBOLS = ["StyleEditor", "StyleEditorFlags", "StyleEditorManager"];
+const EXPORTED_SYMBOLS = ["StyleEditor", "StyleEditorFlags"];
 
 const Cc = Components.classes;
 const Ci = Components.interfaces;
@@ -1160,133 +1160,3 @@ function setupBracketCompletion(aSourceEditor)
     aSourceEditor.setCaretOffset(aSourceEditor.getCaretOffset() - 1);
   }, false);
 }
-
-/**
-  * Manage the different editors instances.
-  */
-
-function StyleEditorManager(aWindow) {
-  this.chromeWindow = aWindow;
-  this.listenToTabs();
-  this.editors = new Map();
-}
-
-StyleEditorManager.prototype = {
-
-  /**
-   * Get the editor for a specific content window.
-   */
-  getEditorForWindow: function SEM_getEditorForWindow(aContentWindow) {
-    return this.editors.get(aContentWindow);
-  },
-
-  /**
-   * Focus the editor and select a stylesheet.
-   *
-   * @param {CSSStyleSheet} [aSelectedStyleSheet] default Stylesheet.
-   * @param {Number} [aLine] Line to which the caret should be moved (one-indexed).
-   * @param {Number} [aCol] Column to which the caret should be moved (one-indexed).
-   */
-  selectEditor: function SEM_selectEditor(aWindow, aSelectedStyleSheet, aLine, aCol) {
-    if (aSelectedStyleSheet) {
-      aWindow.styleEditorChrome.selectStyleSheet(aSelectedStyleSheet, aLine, aCol);
-    }
-    aWindow.focus();
-  },
-
-  /**
-   * Open a new editor.
-   *
-   * @param {Window} content window.
-   * @param {CSSStyleSheet} [aSelectedStyleSheet] default Stylesheet.
-   * @param {Number} [aLine] Line to which the caret should be moved (one-indexed).
-   * @param {Number} [aCol] Column to which the caret should be moved (one-indexed).
-   */
-  newEditor: function SEM_newEditor(aContentWindow, aSelectedStyleSheet, aLine, aCol) {
-    const CHROME_URL = "chrome://browser/content/styleeditor.xul";
-    const CHROME_WINDOW_FLAGS = "chrome,centerscreen,resizable,dialog=no";
-
-    let args = {
-      contentWindow: aContentWindow,
-      selectedStyleSheet: aSelectedStyleSheet,
-      line: aLine,
-      col: aCol
-    };
-    args.wrappedJSObject = args;
-    let chromeWindow = Services.ww.openWindow(null, CHROME_URL, "_blank",
-                                              CHROME_WINDOW_FLAGS, args);
-
-    chromeWindow.onunload = function() {
-      if (chromeWindow.location == CHROME_URL) {
-        // not about:blank being unloaded
-        this.unregisterEditor(aContentWindow);
-      }
-    }.bind(this);
-    chromeWindow.focus();
-
-    this.editors.set(aContentWindow, chromeWindow);
-
-    this.refreshCommand();
-
-    return chromeWindow;
-  },
-
-  /**
-   * Toggle an editor.
-   *
-   * @param {Window} associated content window.
-   */
-  toggleEditor: function SEM_toggleEditor(aContentWindow) {
-    let editor = this.getEditorForWindow(aContentWindow);
-    if (editor) {
-      editor.close();
-    } else {
-      this.newEditor(aContentWindow);
-    }
-  },
-
-  /**
-   * Close an editor.
-   *
-   * @param {Window} associated content window.
-   */
-  unregisterEditor: function SEM_unregisterEditor(aContentWindow) {
-    let chromeWindow = this.editors.get(aContentWindow);
-    if (chromeWindow) {
-      chromeWindow.close();
-    }
-    this.editors.delete(aContentWindow);
-    this.refreshCommand();
-  },
-
-  /**
-   * Update the status of tool's menuitems and buttons.
-   */
-  refreshCommand: function SEM_refreshCommand() {
-    let contentWindow = this.chromeWindow.gBrowser.contentWindow;
-    let command = this.chromeWindow.document.getElementById("Tools:StyleEditor");
-
-    let win = this.getEditorForWindow(contentWindow);
-    if (win) {
-      command.setAttribute("checked", "true");
-    } else {
-      command.setAttribute("checked", "false");
-    }
-  },
-
-  /**
-   * Trigger refreshCommand when needed.
-   */
-  listenToTabs: function SEM_listenToTabs() {
-    let win = this.chromeWindow;
-    let tabs = win.gBrowser.tabContainer;
-
-    let bound_refreshCommand = this.refreshCommand.bind(this);
-    tabs.addEventListener("TabSelect", bound_refreshCommand, true);
-
-    win.addEventListener("unload", function onClose(aEvent) {
-      tabs.removeEventListener("TabSelect", bound_refreshCommand, true);
-      win.removeEventListener("unload", onClose, false);
-    }, false);
-  },
-}