diff --git a/mozilla/modules/libpref/src/init/all.js b/mozilla/modules/libpref/src/init/all.js
index 83016612b3c..7c04d25f72e 100644
--- a/mozilla/modules/libpref/src/init/all.js
+++ b/mozilla/modules/libpref/src/init/all.js
@@ -115,6 +115,7 @@ pref("browser.chrome.toolbar_style",        2);
 pref("browser.toolbars.showbutton.bookmarks", true);
 pref("browser.toolbars.showbutton.go",      false);
 pref("browser.toolbars.showbutton.home",    true);
+pref("browser.toolbars.showbutton.sidebar", true);
 pref("browser.toolbars.showbutton.mynetscape", true);
 pref("browser.toolbars.showbutton.net2phone", true);
 pref("browser.toolbars.showbutton.print",   true);
diff --git a/mozilla/themes/classic/communicator/sidebar/sb-closed.gif b/mozilla/themes/classic/communicator/sidebar/sb-closed.gif
new file mode 100644
index 00000000000..68a2241828f
Binary files /dev/null and b/mozilla/themes/classic/communicator/sidebar/sb-closed.gif differ
diff --git a/mozilla/themes/classic/communicator/sidebar/sb-open.gif b/mozilla/themes/classic/communicator/sidebar/sb-open.gif
new file mode 100644
index 00000000000..8cefb27471a
Binary files /dev/null and b/mozilla/themes/classic/communicator/sidebar/sb-open.gif differ
diff --git a/mozilla/themes/classic/communicator/sidebar/sidebar.css b/mozilla/themes/classic/communicator/sidebar/sidebar.css
index 64f8ef86dcd..6c16c2c9110 100644
--- a/mozilla/themes/classic/communicator/sidebar/sidebar.css
+++ b/mozilla/themes/classic/communicator/sidebar/sidebar.css
@@ -28,6 +28,18 @@
 
 @namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
   
+/* ::::: sidebar toggle button (on personal toolbar) ::::: */
+
+#sidebar-button[sbopen="true"] {
+  list-style-image: url("chrome://communicator/skin/sidebar/sb-open.gif");
+}
+
+#sidebar-button[sbopen="false"] {
+  list-style-image: url("chrome://communicator/skin/sidebar/sb-closed.gif");
+}
+
+/* ::::: sidebar container ::::: */
+
 #sidebar-box {
   border-left: 1px solid ThreeDShadow;
   border-right: 1px solid ThreeDHighlight;
diff --git a/mozilla/themes/classic/jar.mn b/mozilla/themes/classic/jar.mn
index fb6fa7af95c..dee2aa13306 100644
--- a/mozilla/themes/classic/jar.mn
+++ b/mozilla/themes/classic/jar.mn
@@ -45,6 +45,8 @@ classic.jar:
   skin/classic/communicator/search/search-editor.css                    (communicator/search/search-editor.css)
   skin/classic/communicator/search/search.css                           (communicator/search/search.css)
   skin/classic/communicator/search/internetresults.css                  (communicator/search/internetresults.css)
+  skin/classic/communicator/sidebar/sb-open.gif                         (communicator/sidebar/sb-open.gif)
+  skin/classic/communicator/sidebar/sb-closed.gif                       (communicator/sidebar/sb-closed.gif)
   skin/classic/communicator/sidebar/sbtab-twisty.gif                    (communicator/sidebar/sbtab-twisty.gif)
   skin/classic/communicator/sidebar/sbtab-twisty-open.gif               (communicator/sidebar/sbtab-twisty-open.gif)
   skin/classic/communicator/sidebar/customize.css                       (communicator/sidebar/customize.css)
diff --git a/mozilla/themes/modern/communicator/sidebar/sb-closed.gif b/mozilla/themes/modern/communicator/sidebar/sb-closed.gif
new file mode 100644
index 00000000000..68a2241828f
Binary files /dev/null and b/mozilla/themes/modern/communicator/sidebar/sb-closed.gif differ
diff --git a/mozilla/themes/modern/communicator/sidebar/sb-open.gif b/mozilla/themes/modern/communicator/sidebar/sb-open.gif
new file mode 100644
index 00000000000..8cefb27471a
Binary files /dev/null and b/mozilla/themes/modern/communicator/sidebar/sb-open.gif differ
diff --git a/mozilla/themes/modern/communicator/sidebar/sidebar.css b/mozilla/themes/modern/communicator/sidebar/sidebar.css
index 27ffb1df7b0..7710ca2dc1b 100644
--- a/mozilla/themes/modern/communicator/sidebar/sidebar.css
+++ b/mozilla/themes/modern/communicator/sidebar/sidebar.css
@@ -41,6 +41,18 @@
 
 @namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
 
+/* ::::: sidebar toggle button (on personal toolbar) ::::: */
+
+#sidebar-button[sbopen="true"] {
+  list-style-image: url("chrome://communicator/skin/sidebar/sb-open.gif");
+}
+
+#sidebar-button[sbopen="false"] {
+  list-style-image: url("chrome://communicator/skin/sidebar/sb-closed.gif");
+}
+
+/* ::::: sidebar container ::::: */
+
 #sidebar-box {
   border-left: 1px solid #8998AA;
   background-color: #C1CBD5;
diff --git a/mozilla/themes/modern/jar.mn b/mozilla/themes/modern/jar.mn
index bb9de43b1bf..b65fd184680 100644
--- a/mozilla/themes/modern/jar.mn
+++ b/mozilla/themes/modern/jar.mn
@@ -57,6 +57,8 @@ modern.jar:
   skin/modern/communicator/search/search.css                       (communicator/search/search.css)
   skin/modern/communicator/alerts/alert.css                        (communicator/alerts/alert.css)
   skin/modern/communicator/sidebar/sidebarBindings.xml             (communicator/sidebar/sidebarBindings.xml)
+  skin/modern/communicator/sidebar/sb-open.gif                     (communicator/sidebar/sb-open.gif)
+  skin/modern/communicator/sidebar/sb-closed.gif                   (communicator/sidebar/sb-closed.gif)
   skin/modern/communicator/sidebar/sbtab-rit-top-act.gif           (communicator/sidebar/sbtab-rit-top-act.gif)
   skin/modern/communicator/sidebar/sbtab-rit-btm-act.gif           (communicator/sidebar/sbtab-rit-btm-act.gif)
   skin/modern/communicator/sidebar/sbtab-rit-top.gif               (communicator/sidebar/sbtab-rit-top.gif)
diff --git a/mozilla/xpfe/components/sidebar/resources/locale/en-US/sidebarOverlay.dtd b/mozilla/xpfe/components/sidebar/resources/locale/en-US/sidebarOverlay.dtd
index a5982b514fb..21921b323e6 100644
--- a/mozilla/xpfe/components/sidebar/resources/locale/en-US/sidebarOverlay.dtd
+++ b/mozilla/xpfe/components/sidebar/resources/locale/en-US/sidebarOverlay.dtd
@@ -45,4 +45,5 @@
 
 <!ENTITY sidebar.pagenotfound.label  "This tab is not available right now.">
 <!ENTITY sidebar.close.tooltip       "Close Sidebar">
+<!ENTITY sidebar.open.tooltip        "Open Sidebar">
 
diff --git a/mozilla/xpfe/components/sidebar/resources/sidebarOverlay.js b/mozilla/xpfe/components/sidebar/resources/sidebarOverlay.js
index ce8a8f8271e..a770fc104aa 100644
--- a/mozilla/xpfe/components/sidebar/resources/sidebarOverlay.js
+++ b/mozilla/xpfe/components/sidebar/resources/sidebarOverlay.js
@@ -704,9 +704,15 @@ function refresh_all_sidebars() {
 // Sidebar Init
 //////////////////////////////////////////////////////////////
 function sidebar_overlay_init() {
+
+  // do we have a sidebar?
+  if (!document.getElementById("sidebar-panels-splitter-box")) 
+    return;
+
   if (sidebar_is_collapsed() && !gAboutToUncollapse)
     return;
   gMustInit = false;
+  
   sidebarObj.panels = new sbPanelList('sidebar-panels');
   sidebarObj.datasource_uri = get_sidebar_datasource_uri();
   sidebarObj.resource = 'urn:sidebar:current-panel-list';
@@ -733,6 +739,9 @@ function sidebar_overlay_init() {
     if (sidebarObj.never_built) {
       sidebarObj.never_built = false;
 
+      // set personal toolbar sidebar icon to correct state
+      SidebarToggleIcon();
+
       debug("sidebar = " + sidebarObj);
       debug("sidebarObj.resource = " + sidebarObj.resource);
       debug("sidebarObj.datasource_uri = " + sidebarObj.datasource_uri);
@@ -780,9 +789,14 @@ function sidebar_overlay_init() {
 }
 
 function sidebar_overlay_destruct() {
-    var panels = document.getElementById('sidebar-panels');
-    debug("Removing observer from database.");
-    panels.database.RemoveObserver(panel_observer);
+
+  // do we have a sidebar?
+  if (!document.getElementById("sidebar-panels-splitter-box")) 
+    return;
+
+  var panels = document.getElementById('sidebar-panels');
+  debug("Removing observer from database.");
+  panels.database.RemoveObserver(panel_observer);
 }
 
 function sidebar_open_default_panel(wait, tries) {
@@ -1091,6 +1105,7 @@ function sidebar_is_collapsed() {
 }
 
 function SidebarExpandCollapse() {
+  SidebarToggleIcon();
   var sidebar_splitter = document.getElementById('sidebar-splitter');
   var sidebar_box = document.getElementById('sidebar-box');
   if (sidebar_splitter.getAttribute('state') == 'collapsed') {
@@ -1117,6 +1132,7 @@ function sidebar_is_hidden() {
 // Show/Hide the entire sidebar.
 // Invoked by the "View / Sidebar" menu option.
 function SidebarShowHide() {
+  SidebarToggleIcon();
   var sidebar_box = document.getElementById('sidebar-box');
   var title_box = document.getElementById('sidebar-title-box');
   var sidebar_panels_splitter = document.getElementById('sidebar-panels-splitter');
@@ -1299,6 +1315,27 @@ function SidebarTogglePanel(panel_menuitem) {
   sidebarObj.datasource.QueryInterface(Components.interfaces.nsIRDFRemoteDataSource).Flush();
 }
 
+function SidebarToggleIcon()
+{
+  var sidebarButton = document.getElementById("sidebar-button");
+  if (sidebarButton)
+  {
+    var newValue = false;
+    if (sidebarButton.getAttribute("sbopen") == "false")
+      newValue = true;
+
+    sidebarButton.setAttribute("sbopen", newValue);
+
+    var tooltipText;
+    if (newValue) // it's open so show action ``<== Close Sidebar''
+      tooltipText = sidebarButton.getAttribute("sbclosetooltip");
+    else // it's closed so show action ``==> Open Sidebar''
+      tooltipText = sidebarButton.getAttribute("sbopentooltip");
+
+    sidebarButton.setAttribute("tooltiptext", tooltipText);
+  }
+}
+
 function SidebarNavigate(aDirection)
 {
   debug("SidebarNavigate " + aDirection);
diff --git a/mozilla/xpfe/components/sidebar/resources/sidebarOverlay.xul b/mozilla/xpfe/components/sidebar/resources/sidebarOverlay.xul
index 3bb805ad90b..f9bc1fa3069 100644
--- a/mozilla/xpfe/components/sidebar/resources/sidebarOverlay.xul
+++ b/mozilla/xpfe/components/sidebar/resources/sidebarOverlay.xul
@@ -21,7 +21,7 @@
  
 <?xml-stylesheet href="chrome://communicator/content/sidebar/sidebarOverlay.css" type="text/css"?> 
 <?xml-stylesheet href="chrome://global/skin/button.css" type="text/css"?> 
-<?xul-overlay href="chrome://communicator/content/contentAreaContextOverlay.xul"?>
+<?xul-overlay href="chrome://communicator/content/contentAreaContextOverlay.xul"?> 
 
 <!DOCTYPE window [
 <!ENTITY % sidebarOverlayDTD SYSTEM "chrome://communicator/locale/sidebar/sidebarOverlay.dtd" >
@@ -54,6 +54,42 @@
               oncommand="SidebarCustomize();"/>
   </popup>
 
+
+  <!-- insert the sidebar toggle button in the personal toolbar -->
+  <toolbar id="PersonalToolbar">
+    <toolbarbutton id="sidebar-button" position="1"
+                   sbopen="false" 
+                   tooltiptext="&sidebar.open.tooltip;"
+                   sbopentooltip="&sidebar.open.tooltip;"
+                   sbclosetooltip="&sidebar.close.tooltip;"
+                   oncommand="if (sidebar_is_hidden()) SidebarShowHide(); else SidebarExpandCollapse(); event.preventBubble();"/>
+    <toolbarseparator persist="hidden"/>
+  </toolbar>
+
+  <!-- add a pref for the sidebar toggle button -->
+  <vbox id="prefShowButtonsBox1">
+    <checkbox id="sidebarToggleButton"
+              label="&sidebar.panels.label;"
+              insertafter="homeButton"
+              pref="true"
+              preftype="bool"
+              prefstring="browser.toolbars.showbutton.sidebar"
+              prefattribute="checked"/>
+  </vbox>
+  <script type="application/x-javascript">
+    if (this._elementIDs)
+    {
+      this._elementIDs.push("sidebarToggleButton");
+
+      // add a popupset to quiesce complaints from the cookie context menus
+      const kXULNS = 
+        "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
+      var popupset = document.createElementNS(kXULNS, "popupset");
+      popupset.setAttribute("id", "contentAreaContextSet");
+      document.documentElement.appendChild(popupset);
+    }
+  </script>
+
   <!-- Overlay the sidebar panels -->
   <vbox id="sidebar-box" persist="hidden width collapsed">
     <splitter id="sidebar-panels-splitter" collapse="after" persist="state"