// this is a pointer to the mail TB window
var mailWindow = Components.classes["@mozilla.org/appshell/window-mediator;1"].getService()
                     .QueryInterface(Components.interfaces.nsIWindowMediator)
                     .getMostRecentWindow("mail:3pane");
//this is a pointer to the currently selected message
var messageDetails = mailWindow.GetLoadedMessage()
// if the pointer is valid ..
if (messageDetails) {
    // this is a pointer to the message header of the current message
    var messageHdr = mailWindow.messenger.messageServiceFromURI(messageDetails).messageURIToMsgHdr(messageDetails);
    // the date is in Microseconds !
    var stdate = new Date(messageHdr.date / 1000);
    var dateService = Components.classes["@mozilla.org/intl/scriptabledateformat;1"].getService(Components.interfaces.nsIScriptableDateFormat);
    // format it according to the current locale's date spec
    var stdt = dateService.FormatDateTime("", dateService.dateFormatLong, dateService.timeFormatSeconds, stdate.getFullYear(), stdate.getMonth()+1, stdate.getDate(), stdate.getHours(), stdate.getMinutes(), stdate.getSeconds());
    // this is where we start to create the new header
    var newheader = '-----Original Message-----\n';
    newheader += 'From: ' + messageHdr.author + '\n';
    newheader += 'To: ' + messageHdr.recipients + '\n'
    newheader += 'Sent: ' + stdt + '\n';
    newheader += 'Subject: ' + messageHdr.subject;
    //the new header is done, now lets get the stock header

    // this is a pointer to the body portion of the compose window
    var fded = GetCurrentEditor()
    var fddom = fded.rootElement;
    // these childnodes are every one of the items already in the body ( the header, quoted text, etc)
    var fddomnodes = fddom.childNodes;
    // lets chew through all of the nodes looking for text that matches 'wrote, On'
    var a_node;
    for (i=0; i < fddomnodes.length ; i++ ) {
       a_node = fddomnodes[i];
        // some nodes are NOT text (HTML BRs and SPANs) so we will put a try/catch block around the check
       try {
          if (a_node.nodeValue.indexOf('wrote, On') > 0) {
            // found the standard header text, lets change it now
           try {
                // lets create a span node to hold our new header
                var nht = fded.createElementWithDefaults("span");
                // we need to change < chars (like from <someone@somewhere.com>) to ctrl chars
                var re = /</gi;
                newheader = newheader.replace(re,'&lt;');
                // we need to change < chars (like from <someone@somewhere.com>) to ctrl chars
                var re = />/gi;
                newheader = newheader.replace(re,'&gt;');
                // lets change all \n (newline) control chars to <BR>
                var re = /\n/gi;
                newheader = newheader.replace(re,'<BR>');
                // lets set the span node's inner html to the hew header text
                nht.innerHTML = newheader;
                // we do not want the caret's position to change while we are adding and deleting nodes
                fded.setShouldTxnSetSelection(false);
                fded.beginTransaction();
                // this will ALWAYS insert the node just after the node we are going to delete
                fded.insertNode(nht,fddom,i+1);
                fded.endTransaction();
                // THIS IS VERY IMPORTANT, if we do not do this, TB crashes
                fded.setShouldTxnSetSelection(true);
                // ok so we added the node, now lets delete the old header node
                fded.deleteNode(a_node);
            } catch(e) { 
                alert(e);
            }
            // if the body text is big enough for the scroll bar to show, once we add the new header, 
            //  we don't see the caret anymore, this will make scroll the caret into view
            try {
                var selectionController = fded.selectionController;
                selectionController.scrollSelectionIntoView(selectionController.SELECTION_NORMAL, selectionController.SELECTION_ANCHOR_REGION, true);
            } catch (e) { 
                alert(e)
            }
            // lets set i so high that we immediately exit the for loop
            i = 7000
          }
       } catch (e) {}
    }
}
// Done !