diff --git a/widget/src/gtk/nsGtkEventHandler.cpp b/widget/src/gtk/nsGtkEventHandler.cpp
index 41b832e118b0..b2e060a4d005 100644
--- a/widget/src/gtk/nsGtkEventHandler.cpp
+++ b/widget/src/gtk/nsGtkEventHandler.cpp
@@ -456,6 +456,7 @@ gint nsGtkWidget_Scrollbar_Callback(GtkWidget *w, gpointer p)
   sevent.message = NS_SCROLLBAR_POS;
   sevent.widget  = (nsWidget *) p;
   widget->OnScroll(sevent, GTK_ADJUSTMENT(w)->value);
+  return 0; /* XXX */
 }
 
 
@@ -478,6 +479,7 @@ gint nsGtkWidget_Expose_Callback(GtkWidget *w, gpointer p)
   pevent.rect = (nsRect *)▭
   widgetWindow->OnPaint(pevent);
 #endif
+  return 0; /* XXX */
 }
 
 //==============================================================
@@ -522,6 +524,7 @@ gint nsGtkWidget_Text_Callback(GtkWidget *w, GdkEvent* event, gpointer p)
   for (len = 0; len < cbs->text->length; len++)
     cbs->text->ptr[len] = '*';
 #endif
+  return 0; /* XXX */
 }
 
 //==============================================================
diff --git a/widget/src/gtk/nsScrollbar.cpp b/widget/src/gtk/nsScrollbar.cpp
index b7873e8a958c..f0877f99e5d0 100644
--- a/widget/src/gtk/nsScrollbar.cpp
+++ b/widget/src/gtk/nsScrollbar.cpp
@@ -265,6 +265,7 @@ int nsScrollbar::AdjustScrollBarPosition(int aPosition)
   int cap = maxRange - sliderSize;
   return aPosition > cap ? cap : aPosition;
 #endif
+  return 0;  /* XXX */
 }
 
 //-------------------------------------------------------------------------
diff --git a/widget/src/gtk/nsWidget.cpp b/widget/src/gtk/nsWidget.cpp
index 2c96be43f118..945d5aa3b230 100644
--- a/widget/src/gtk/nsWidget.cpp
+++ b/widget/src/gtk/nsWidget.cpp
@@ -73,6 +73,7 @@ NS_METHOD nsWidget::ScreenToWidget(const nsRect& aOldRect, nsRect& aNewRect)
 NS_IMETHODIMP nsWidget::Destroy(void)
 {
   ::gtk_widget_destroy(mWidget);
+  return NS_OK;
 }
 
 //-------------------------------------------------------------------------
diff --git a/widget/src/gtk/nsWidget.h b/widget/src/gtk/nsWidget.h
index 8adb61fc8645..a152f27e990e 100644
--- a/widget/src/gtk/nsWidget.h
+++ b/widget/src/gtk/nsWidget.h
@@ -120,7 +120,7 @@ class nsWidget : public nsBaseWidget
     virtual void InitCallbacks(char * aName = nsnull);
     void CreateGC();
 
-    NS_IMETHOD CreateNative(GtkWidget *parentWindow) {};
+    NS_IMETHOD CreateNative(GtkWidget *parentWindow) { return NS_OK; }
 
     nsresult StandardWindowCreate(nsIWidget *aParent,
                       const nsRect &aRect,
diff --git a/widget/src/gtk/nsWindow.cpp b/widget/src/gtk/nsWindow.cpp
index 032d5c5ef2ae..09300be90ca4 100644
--- a/widget/src/gtk/nsWindow.cpp
+++ b/widget/src/gtk/nsWindow.cpp
@@ -226,6 +226,7 @@ NS_METHOD nsWindow::CreateNative(GtkWidget *parentWidget)
   gtk_widget_set_name(mWidget, "nsWindow");
   mCursor = eCursor_select;
   SetCursor(eCursor_standard);
+  return NS_OK;
 }