Mine

<?xml version="1.0"?>
<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>

<window
   title      = "The Window"
   id         = "mainWindow"
   xmlns      = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
   xmlns:xhtml = "http://www.w3.org/1999/xhtml"
   script-type = "application/javascript"
   width      = "640"
   height     = "480"
   orient     = "vertical">

    <script type="application/javascript">
        <![CDATA[
        alert('hello');
        function startEditing() {
            var editor = document.getElementById('editor');
            editor.setAttribute('src', 'about:blank');
            editor.focus();
        }

        function bold() {
            alert("bolding");
            nsIAccessibleProvider = Components.interfaces.nsIAccessibleProvider
            alert("bolding");
            editorElement = document.getElementById('editor')
            from pprint import pprint
            pprint(editorElement._interfaces_.values())
            print editorElement
            #element = editor.getSelectedElement()
        }
        ]]>
    </script>

    <vbox id="staticTextContainer" flex="1">
        <label id="staticTextLabel" value="Static Text"/>
        <!-- 
        <xhtml:div style="-moz-user-modify: read-write; -moz-user-input: enabled; -moz-user-select: normal;"> 
            <h1>Heading</h1>
            <p>
            Some paragraph text
            </p>
        </xhtml:div>
        -->
        <toolbar>
            <toolbarbutton label="Bold" oncommand="bold()"/>
        </toolbar>
        <editor id="editor" name="contents" editortype="html" style="width: 100%; height: 200px; background-color: white;"/>
    </vbox>
</window>