diff -r 000000000000 -r 6474c204b198 layout/xul/nsStackFrame.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/xul/nsStackFrame.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,46 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+
+  Eric D Vaughan
+  A frame that can have multiple children. Only one child may be displayed at one time. So the
+  can be flipped though like a Stack of cards.
+ 
+**/
+
+#ifndef nsStackFrame_h___
+#define nsStackFrame_h___
+
+#include "mozilla/Attributes.h"
+#include "nsBoxFrame.h"
+
+class nsStackFrame : public nsBoxFrame
+{
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+
+  friend nsIFrame* NS_NewStackFrame(nsIPresShell* aPresShell,
+                                    nsStyleContext* aContext);
+
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const MOZ_OVERRIDE
+  {
+    return MakeFrameName(NS_LITERAL_STRING("Stack"), aResult);
+  }
+#endif
+
+  virtual void BuildDisplayListForChildren(nsDisplayListBuilder*   aBuilder,
+                                           const nsRect&           aDirtyRect,
+                                           const nsDisplayListSet& aLists) MOZ_OVERRIDE;
+
+protected:
+  nsStackFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
+}; // class nsStackFrame
+
+
+
+#endif
+