diff -r 000000000000 -r 6474c204b198 editor/libeditor/base/PlaceholderTxn.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/editor/libeditor/base/PlaceholderTxn.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,80 @@
+/* -*- 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/. */
+
+#ifndef AggregatePlaceholderTxn_h__
+#define AggregatePlaceholderTxn_h__
+
+#include "EditAggregateTxn.h"
+#include "nsEditorUtils.h"
+#include "nsIAbsorbingTransaction.h"
+#include "nsIDOMNode.h"
+#include "nsCOMPtr.h"
+#include "nsWeakPtr.h"
+#include "nsWeakReference.h"
+#include "nsAutoPtr.h"
+
+class nsHTMLEditor;
+class IMETextTxn;
+
+/**
+ * An aggregate transaction that knows how to absorb all subsequent
+ * transactions with the same name.  This transaction does not "Do" anything.
+ * But it absorbs other transactions via merge, and can undo/redo the
+ * transactions it has absorbed.
+ */
+ 
+class PlaceholderTxn : public EditAggregateTxn, 
+                       public nsIAbsorbingTransaction, 
+                       public nsSupportsWeakReference
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED  
+  
+  PlaceholderTxn();
+
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(PlaceholderTxn, EditAggregateTxn)
+// ------------ EditAggregateTxn -----------------------
+
+  NS_DECL_EDITTXN
+
+  NS_IMETHOD RedoTransaction();
+  NS_IMETHOD Merge(nsITransaction *aTransaction, bool *aDidMerge);
+
+// ------------ nsIAbsorbingTransaction -----------------------
+
+  NS_IMETHOD Init(nsIAtom* aName, nsSelectionState* aSelState,
+                  nsEditor* aEditor);
+  
+  NS_IMETHOD GetTxnName(nsIAtom **aName);
+  
+  NS_IMETHOD StartSelectionEquals(nsSelectionState *aSelState, bool *aResult);
+
+  NS_IMETHOD EndPlaceHolderBatch();
+
+  NS_IMETHOD ForwardEndBatchTo(nsIAbsorbingTransaction *aForwardingAddress);
+
+  NS_IMETHOD Commit();
+
+  NS_IMETHOD RememberEndingSelection();
+
+protected:
+
+  /** the presentation shell, which we'll need to get the selection */
+  bool        mAbsorb;          // do we auto absorb any and all transaction?
+  nsWeakPtr   mForwarding;
+  IMETextTxn *mIMETextTxn;      // first IME txn in this placeholder - used for IME merging
+                                // non-owning for now - can't nsCOMPtr it due to broken transaction interfaces
+  bool        mCommitted;       // do we stop auto absorbing any matching placeholder txns?
+  // these next two members store the state of the selection in a safe way. 
+  // selection at the start of the txn is stored, as is the selection at the end.
+  // This is so that UndoTransaction() and RedoTransaction() can restore the
+  // selection properly.
+  nsAutoPtr<nsSelectionState> mStartSel; // use a pointer because this is constructed before we exist
+  nsSelectionState  mEndSel;
+  nsEditor*         mEditor;   /** the editor for this transaction */
+};
+
+
+#endif