diff -r 000000000000 -r 6474c204b198 layout/xul/tree/nsTreeColFrame.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/xul/tree/nsTreeColFrame.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,56 @@
+/* -*- 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/. */
+
+#include "mozilla/Attributes.h"
+#include "nsBoxFrame.h"
+
+class nsITreeBoxObject;
+
+nsIFrame* NS_NewTreeColFrame(nsIPresShell* aPresShell, 
+                             nsStyleContext* aContext);
+
+class nsTreeColFrame : public nsBoxFrame
+{
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+
+  nsTreeColFrame(nsIPresShell* aPresShell,
+                 nsStyleContext* aContext):
+    nsBoxFrame(aPresShell, aContext) {}
+
+  virtual void Init(nsIContent*      aContent,
+                    nsIFrame*        aParent,
+                    nsIFrame*        aPrevInFlow) MOZ_OVERRIDE;
+
+  virtual void DestroyFrom(nsIFrame* aDestructRoot) MOZ_OVERRIDE;
+
+  virtual void BuildDisplayListForChildren(nsDisplayListBuilder*   aBuilder,
+                                           const nsRect&           aDirtyRect,
+                                           const nsDisplayListSet& aLists) MOZ_OVERRIDE;
+
+  virtual nsresult AttributeChanged(int32_t aNameSpaceID,
+                                    nsIAtom* aAttribute,
+                                    int32_t aModType) MOZ_OVERRIDE;
+
+  virtual void SetBounds(nsBoxLayoutState& aBoxLayoutState, const nsRect& aRect,
+                         bool aRemoveOverflowArea = false) MOZ_OVERRIDE;
+
+  friend nsIFrame* NS_NewTreeColFrame(nsIPresShell* aPresShell,
+                                      nsStyleContext* aContext);
+
+protected:
+  virtual ~nsTreeColFrame();
+
+  /**
+   * @return the tree box object of the tree this column belongs to, or nullptr.
+   */
+  nsITreeBoxObject* GetTreeBoxObject();
+
+  /**
+   * Helper method that gets the nsITreeColumns object this column belongs to
+   * and calls InvalidateColumns() on it.
+   */
+  void InvalidateColumns(bool aCanWalkFrameTree = true);
+};