diff --git a/editor/base/nsJSTxnLog.cpp b/editor/base/nsJSTxnLog.cpp
new file mode 100644
index 000000000000..9d1b0e42d8d9
--- /dev/null
+++ b/editor/base/nsJSTxnLog.cpp
@@ -0,0 +1,288 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * The contents of this file are subject to the Netscape Public License
+ * Version 1.0 (the "NPL"); you may not use this file except in
+ * compliance with the NPL.  You may obtain a copy of the NPL at
+ * http://www.mozilla.org/NPL/
+ *
+ * Software distributed under the NPL is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
+ * for the specific language governing rights and limitations under the
+ * NPL.
+ *
+ * The Initial Developer of this code under the NPL is Netscape
+ * Communications Corporation.  Portions created by Netscape are
+ * Copyright (C) 1998 Netscape Communications Corporation.  All Rights
+ * Reserved.
+ */
+
+#include <stdio.h>
+#include "nsJSTxnLog.h"
+
+#define LOCK_LOG(doc)
+#define UNLOCK_LOG(doc)
+
+static NS_DEFINE_IID(kISupportsIID, NS_ISUPPORTS_IID);
+
+nsJSTxnLog::nsJSTxnLog()
+{
+  mRefCnt      = 0;
+  mIndentLevel = 0;
+  mBatchCount  = 0;
+}
+
+nsJSTxnLog::~nsJSTxnLog()
+{
+}
+
+#define DEBUG_JS_TXN_LOG_REFCNT 1
+
+#ifdef DEBUG_JS_TXN_LOG_REFCNT
+
+nsrefcnt nsJSTxnLog::AddRef(void)
+{
+  return ++mRefCnt;
+}
+
+nsrefcnt nsJSTxnLog::Release(void)
+{
+  NS_PRECONDITION(0 != mRefCnt, "dup release");
+  if (--mRefCnt == 0) {
+    NS_DELETEXPCOM(this);
+    return 0;
+  }
+  return mRefCnt;
+}
+
+#else
+
+NS_IMPL_ADDREF(nsJSTxnLog)
+NS_IMPL_RELEASE(nsJSTxnLog)
+
+#endif
+
+NS_IMETHODIMP
+nsJSTxnLog::QueryInterface(REFNSIID aIID, void** aInstancePtr)
+{
+  if (nsnull == aInstancePtr) {
+    return NS_ERROR_NULL_POINTER;
+  }
+  if (aIID.Equals(kISupportsIID)) {
+    *aInstancePtr = (void*)(nsISupports*)this;
+    NS_ADDREF_THIS();
+    return NS_OK;
+  }
+  if (aIID.Equals(nsITransactionListener::GetIID())) {
+    *aInstancePtr = (void*)(nsITransactionListener*)this;
+    NS_ADDREF_THIS();
+    return NS_OK;
+  }
+  *aInstancePtr = 0;
+  return NS_NOINTERFACE;
+}
+
+NS_IMETHODIMP
+nsJSTxnLog::WillDo(nsITransactionManager *aTxMgr, nsITransaction *aTransaction)
+{
+  LOCK_LOG(this);
+
+  PrintIndent(mIndentLevel++);
+  printf("WillDo:   %s\n", GetString(aTransaction));
+
+  UNLOCK_LOG(this);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsJSTxnLog::DidDo(nsITransactionManager *aTxMgr, nsITransaction *aTransaction, nsresult aDoResult)
+{
+  LOCK_LOG(this);
+
+  PrintIndent(--mIndentLevel);
+  printf("DidDo:    %s (%d)\n", GetString(aTransaction), aDoResult);
+
+  UNLOCK_LOG(this);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsJSTxnLog::WillUndo(nsITransactionManager *aTxMgr, nsITransaction *aTransaction)
+{
+  LOCK_LOG(this);
+
+  PrintIndent(mIndentLevel++);
+
+  if (aTransaction)
+    printf("WillUndo: %s\n", GetString(aTransaction));
+  else
+    printf("WillUndoBatch\n");
+
+  UNLOCK_LOG(this);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsJSTxnLog::DidUndo(nsITransactionManager *aTxMgr, nsITransaction *aTransaction, nsresult aUndoResult)
+{
+  LOCK_LOG(this);
+
+  PrintIndent(--mIndentLevel);
+
+  if (aTransaction)
+    printf("DidUndo:  %s (%d)\n", GetString(aTransaction), aUndoResult);
+  else
+    printf("EndUndoBatch (%d)\n", aUndoResult);
+
+  UNLOCK_LOG(this);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsJSTxnLog::WillRedo(nsITransactionManager *aTxMgr, nsITransaction *aTransaction)
+{
+  LOCK_LOG(this);
+
+  PrintIndent(mIndentLevel++);
+
+  if (aTransaction)
+    printf("WillRedo: %s\n", GetString(aTransaction));
+  else
+    printf("WillRedoBatch\n");
+
+  UNLOCK_LOG(this);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsJSTxnLog::DidRedo(nsITransactionManager *aTxMgr, nsITransaction *aTransaction, nsresult aRedoResult)
+{
+  LOCK_LOG(this);
+
+  PrintIndent(--mIndentLevel);
+
+  if (aTransaction)
+    printf("DidRedo:  %s (%d)\n", GetString(aTransaction), aRedoResult);
+  else
+    printf("DidRedoBatch (%d)\n", aRedoResult);
+
+  UNLOCK_LOG(this);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsJSTxnLog::WillBeginBatch(nsITransactionManager *aTxMgr)
+{
+  LOCK_LOG(this);
+
+  PrintIndent(mIndentLevel);
+  printf("WillBeginBatch: %d\n", mBatchCount);
+
+  UNLOCK_LOG(this);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsJSTxnLog::DidBeginBatch(nsITransactionManager *aTxMgr, nsresult aResult)
+{
+  LOCK_LOG(this);
+
+  PrintIndent(mIndentLevel++);
+  printf("DidBeginBatch:  %d (%d)\n", mBatchCount++, aResult);
+
+  UNLOCK_LOG(this);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsJSTxnLog::WillEndBatch(nsITransactionManager *aTxMgr)
+{
+  LOCK_LOG(this);
+
+  PrintIndent(--mIndentLevel);
+  printf("WillEndBatch:   %d\n", --mBatchCount);
+
+  UNLOCK_LOG(this);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsJSTxnLog::DidEndBatch(nsITransactionManager *aTxMgr, nsresult aResult)
+{
+  LOCK_LOG(this);
+
+  PrintIndent(mIndentLevel);
+  printf("DidEndBatch:    %d (%d)\n", mBatchCount, aResult);
+
+  UNLOCK_LOG(this);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsJSTxnLog::WillMerge(nsITransactionManager *aTxMgr, nsITransaction *aTopTransaction, nsITransaction *aTransaction)
+{
+  LOCK_LOG(this);
+
+  PrintIndent(mIndentLevel);
+  printf("WillMerge:   %s <-- %s\n",
+         GetString(aTopTransaction), GetString(aTransaction));
+
+  UNLOCK_LOG(this);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsJSTxnLog::DidMerge(nsITransactionManager *aTxMgr, nsITransaction *aTopTransaction, nsITransaction *aTransaction, PRBool aDidMerge, nsresult aMergeResult)
+{
+  LOCK_LOG(this);
+
+  PrintIndent(mIndentLevel);
+  printf("DidMerge:    %s <-- %s (%s, %d)\n",
+         GetString(aTopTransaction), GetString(aTransaction),
+         aDidMerge ? "TRUE" : "FALSE", aMergeResult);
+
+  UNLOCK_LOG(this);
+
+  return NS_OK;
+}
+
+const char *
+nsJSTxnLog::GetString(nsITransaction *aTransaction)
+{
+  static char buf[256];
+
+  nsString str = "";
+
+  aTransaction->GetRedoString(&str);
+
+  if (str.Length() == 0)
+    str = "<NULL>";
+
+  buf[0] = '\0';
+  str.ToCString(buf, 256);
+
+  return buf;
+}
+
+nsresult
+nsJSTxnLog::PrintIndent(PRInt32 aIndentLevel)
+{
+  PRInt32 i;
+
+  printf("    // ");
+
+  for (i = 0; i < aIndentLevel; i++)
+    printf("  ");
+
+  return NS_OK;
+}
diff --git a/editor/base/nsJSTxnLog.h b/editor/base/nsJSTxnLog.h
new file mode 100644
index 000000000000..8c5fa5c19cbf
--- /dev/null
+++ b/editor/base/nsJSTxnLog.h
@@ -0,0 +1,71 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * The contents of this file are subject to the Netscape Public License
+ * Version 1.0 (the "NPL"); you may not use this file except in
+ * compliance with the NPL.  You may obtain a copy of the NPL at
+ * http://wwwt.mozilla.org/NPL/
+ *
+ * Software distributed under the NPL is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
+ * for the specific language governing rights and limitations under the
+ * NPL.
+ *
+ * The Initial Developer of this code under the NPL is Netscape
+ * Communications Corporation.  Portions created by Netscape are
+ * Copyright (C) 1998 Netscape Communications Corporation.  All Rights
+ * Reserved.
+ */
+
+#ifndef nsJSTxnLog_h__
+#define nsJSTxnLog_h__
+
+#include "nsITransaction.h"
+#include "nsITransactionManager.h"
+#include "nsITransactionListener.h"
+
+/** implementation of a transaction listener object.
+ *
+ */
+class nsJSTxnLog : public nsITransactionListener
+{
+private:
+
+  PRInt32 mIndentLevel;
+  PRInt32 mBatchCount;
+
+public:
+
+  /** The default constructor.
+   */
+  nsJSTxnLog();
+
+  /** The default destructor.
+   */
+  virtual ~nsJSTxnLog();
+
+  /* Macro for AddRef(), Release(), and QueryInterface() */
+  NS_DECL_ISUPPORTS
+
+  /* nsITransactionListener method implementations. */
+  NS_IMETHOD WillDo(nsITransactionManager *aTxMgr, nsITransaction *aTransaction);
+  NS_IMETHOD DidDo(nsITransactionManager *aTxMgr, nsITransaction *aTransaction, nsresult aDoResult);
+  NS_IMETHOD WillUndo(nsITransactionManager *aTxMgr, nsITransaction *aTransaction);
+  NS_IMETHOD DidUndo(nsITransactionManager *aTxMgr, nsITransaction *aTransaction, nsresult aUndoResult);
+  NS_IMETHOD WillRedo(nsITransactionManager *aTxMgr, nsITransaction *aTransaction);
+  NS_IMETHOD DidRedo(nsITransactionManager *aTxMgr, nsITransaction *aTransaction, nsresult aRedoResult);
+  NS_IMETHOD WillBeginBatch(nsITransactionManager *aTxMgr);
+  NS_IMETHOD DidBeginBatch(nsITransactionManager *aTxMgr, nsresult aResult);
+  NS_IMETHOD WillEndBatch(nsITransactionManager *aTxMgr);
+  NS_IMETHOD DidEndBatch(nsITransactionManager *aTxMgr, nsresult aResult);
+  NS_IMETHOD WillMerge(nsITransactionManager *aTxMgr, nsITransaction *aTopTransaction, nsITransaction *aTransaction);
+  NS_IMETHOD DidMerge(nsITransactionManager *aTxMgr, nsITransaction *aTopTransaction, nsITransaction *aTransaction, PRBool aDidMerge, nsresult aMergeResult);
+
+
+private:
+
+  /* nsJSTxnLog private methods. */
+  const char *GetString(nsITransaction *aTransaction);
+  nsresult PrintIndent(PRInt32 aIndentLevel);
+};
+
+#endif // nsJSTxnLog_h__