diff --git a/widget/public/nsIWidget.h b/widget/public/nsIWidget.h
index 951355555eb..eff2ee3cc57 100644
--- a/widget/public/nsIWidget.h
+++ b/widget/public/nsIWidget.h
@@ -973,7 +973,7 @@ class nsIWidget : public nsISupports {
     /**
      * Classify the window for the window manager. Mostly for X11.
      */
-    NS_IMETHOD SetWindowClass(const nsAString& aName, const nsAString& xulWinType) = 0;
+    NS_IMETHOD SetWindowClass(const nsAString& xulWinType) = 0;
 
     /**
      * Enables/Disables system capture of any and all events that would cause a
diff --git a/widget/src/gtk2/nsWindow.cpp b/widget/src/gtk2/nsWindow.cpp
index 449776986ce..f0930ce11c1 100644
--- a/widget/src/gtk2/nsWindow.cpp
+++ b/widget/src/gtk2/nsWindow.cpp
@@ -65,6 +65,7 @@
 #include "nsIPrefService.h"
 #include "nsIPrefBranch.h"
 #include "nsIServiceManager.h"
+#include "nsIStringBundle.h"
 #include "nsGfxCIID.h"
 
 #ifdef ACCESSIBILITY
@@ -2568,6 +2569,27 @@ nsWindow::OnDragEnter(nscoord aX, nscoord aY)
     DispatchEvent(&event, status);
 }
 
+static void
+GetBrandName(nsXPIDLString& brandName)
+{
+    nsCOMPtr<nsIStringBundleService> bundleService = 
+        do_GetService(NS_STRINGBUNDLE_CONTRACTID);
+
+    nsCOMPtr<nsIStringBundle> bundle;
+    if (bundleService)
+        bundleService->CreateBundle(
+            "chrome://branding/locale/brand.properties",
+            getter_AddRefs(bundle));
+
+    if (bundle)
+        bundle->GetStringFromName(
+            NS_LITERAL_STRING("brandShortName").get(),
+            getter_Copies(brandName));
+
+    if (brandName.IsEmpty())
+        brandName.Assign(NS_LITERAL_STRING("Mozilla"));
+}
+
 nsresult
 nsWindow::NativeCreate(nsIWidget        *aParent,
                        nsNativeWidget    aNativeParent,
@@ -2688,9 +2710,15 @@ nsWindow::NativeCreate(nsIWidget        *aParent,
     case eWindowType_toplevel:
     case eWindowType_invisible: {
         mIsTopLevel = PR_TRUE;
+
+        nsXPIDLString brandName;
+        GetBrandName(brandName);
+        NS_ConvertUTF16toUTF8 cBrand(brandName);
+
         if (mWindowType == eWindowType_dialog) {
             mShell = gtk_window_new(GTK_WINDOW_TOPLEVEL);
             SetDefaultIcon();
+            gtk_window_set_wmclass(GTK_WINDOW(mShell), "Dialog", cBrand.get());
             gtk_window_set_type_hint(GTK_WINDOW(mShell),
                                      GDK_WINDOW_TYPE_HINT_DIALOG);
             gtk_window_set_transient_for(GTK_WINDOW(mShell),
@@ -2719,7 +2747,8 @@ nsWindow::NativeCreate(nsIWidget        *aParent,
         }
         else if (mWindowType == eWindowType_popup) {
             mShell = gtk_window_new(GTK_WINDOW_POPUP);
-            gtk_window_set_wmclass(GTK_WINDOW(mShell), "Popup", "Mozilla");
+            gtk_window_set_wmclass(GTK_WINDOW(mShell), "Popup", cBrand.get());
+
             if (topLevelParent) {
                 gtk_window_set_transient_for(GTK_WINDOW(mShell),
                                             topLevelParent);
@@ -2735,7 +2764,7 @@ nsWindow::NativeCreate(nsIWidget        *aParent,
         else { // must be eWindowType_toplevel
             mShell = gtk_window_new(GTK_WINDOW_TOPLEVEL);
             SetDefaultIcon();
-            gtk_window_set_wmclass(GTK_WINDOW(mShell), "Toplevel", "Mozilla");
+            gtk_window_set_wmclass(GTK_WINDOW(mShell), "Toplevel", cBrand.get());
 
             // each toplevel window gets its own window group
             mWindowGroup = gtk_window_group_new();
@@ -2942,12 +2971,14 @@ nsWindow::NativeCreate(nsIWidget        *aParent,
 }
 
 NS_IMETHODIMP
-nsWindow::SetWindowClass(const nsAString& aName,
-                         const nsAString &xulWinType)
+nsWindow::SetWindowClass(const nsAString &xulWinType)
 {
   if (!mShell)
     return NS_ERROR_FAILURE;
 
+  nsXPIDLString brandName;
+  GetBrandName(brandName);
+
   XClassHint *class_hint = XAllocClassHint();
   if (!class_hint)
     return NS_ERROR_OUT_OF_MEMORY;
@@ -2957,7 +2988,7 @@ nsWindow::SetWindowClass(const nsAString& aName,
     XFree(class_hint);
     return NS_ERROR_OUT_OF_MEMORY;
   }
-  class_hint->res_class = ToNewCString(aName);
+  class_hint->res_class = ToNewCString(brandName);
   if (!class_hint->res_class) {
     nsMemory::Free(class_hint->res_name);
     XFree(class_hint);
diff --git a/widget/src/gtk2/nsWindow.h b/widget/src/gtk2/nsWindow.h
index 3e338558f76..3505a811f73 100644
--- a/widget/src/gtk2/nsWindow.h
+++ b/widget/src/gtk2/nsWindow.h
@@ -138,8 +138,7 @@ public:
     NS_IMETHOD         SetBorderStyle(nsBorderStyle aBorderStyle);
     NS_IMETHOD         SetTitle(const nsAString& aTitle);
     NS_IMETHOD         SetIcon(const nsAString& aIconSpec);
-    NS_IMETHOD         SetWindowClass(const nsAString& aName,
-                                      const nsAString& xulWinType);
+    NS_IMETHOD         SetWindowClass(const nsAString& xulWinType);
     NS_IMETHOD         SetMenuBar(nsIMenuBar * aMenuBar);
     NS_IMETHOD         ShowMenuBar(PRBool aShow);
     NS_IMETHOD         WidgetToScreen(const nsRect& aOldRect,
diff --git a/widget/src/xpwidgets/nsBaseWidget.cpp b/widget/src/xpwidgets/nsBaseWidget.cpp
index f3dbebc0a55..50109154b7c 100644
--- a/widget/src/xpwidgets/nsBaseWidget.cpp
+++ b/widget/src/xpwidgets/nsBaseWidget.cpp
@@ -685,8 +685,7 @@ void nsBaseWidget::OnDestroy()
   NS_IF_RELEASE(mToolkit);
 }
 
-NS_METHOD nsBaseWidget::SetWindowClass(const nsAString& aName,
-                                       const nsAString& xulWinType)
+NS_METHOD nsBaseWidget::SetWindowClass(const nsAString& xulWinType)
 {
   return NS_ERROR_NOT_IMPLEMENTED;
 }
diff --git a/widget/src/xpwidgets/nsBaseWidget.h b/widget/src/xpwidgets/nsBaseWidget.h
index f7f6588562f..799f119954c 100644
--- a/widget/src/xpwidgets/nsBaseWidget.h
+++ b/widget/src/xpwidgets/nsBaseWidget.h
@@ -115,8 +115,7 @@ public:
   NS_IMETHOD              SetModal(PRBool aModal); 
   NS_IMETHOD              ModalEventFilter(PRBool aRealEvent, void *aEvent,
                             PRBool *aForWindow);
-  NS_IMETHOD              SetWindowClass(const nsAString& aName,
-                            const nsAString& xulWinType);
+  NS_IMETHOD              SetWindowClass(const nsAString& xulWinType);
   NS_IMETHOD              SetBorderStyle(nsBorderStyle aBorderStyle); 
   NS_IMETHOD              AddMouseListener(nsIMouseListener * aListener);
   NS_IMETHOD              AddEventListener(nsIEventListener * aListener);
diff --git a/xpfe/appshell/src/nsXULWindow.cpp b/xpfe/appshell/src/nsXULWindow.cpp
index e441ed919e5..9f1085a5c8d 100644
--- a/xpfe/appshell/src/nsXULWindow.cpp
+++ b/xpfe/appshell/src/nsXULWindow.cpp
@@ -1337,7 +1337,7 @@ NS_IMETHODIMP nsXULWindow::LoadWindowClassFromXUL()
                                 windowType);
 
   if (!windowType.IsEmpty()) {
-    mWindow->SetWindowClass(NS_LITERAL_STRING("Mozilla"), windowType);
+    mWindow->SetWindowClass(windowType);
   }
 
   return NS_OK;