Textbox code help

Is there a way to get a string or any other code to appear in a vbox textbox?  I was thinking back to my VB days is there other kinds of textboxes so to say that will allow one to place a code into a textbox?

value only allows text from what I found.

http://i116.photobucket.com/albums/o26/squiresmurf/Firefox/PermanentBookmarkToolbar007.jpg




    var ipi = XML. ignoreProcessingInstructions;
    XML. ignoreProcessingInstructions = false;
    var dialog = <>
        <?xml-stylesheet href="chrome://global/skin/"?>
        <?xml-stylesheet href="resource://gre/res/html.css"?>
        <dialog xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
                id="dlg02"
                title="Permanent Bookmark Edit Menu Link"
                ondialogaccept="return windowController.accept();">
            <script type="application/x-javascript">
                <![CDATA[
                    var windowController =
                    {
                        accept: function ()
                        {
                            var name = document. getElementById ("nametb"). value;
                            var url = document. getElementById ("urltb"). value;
                            var img = document. getElementById ("imgtb"). value;
                            window. arguments [0] (name, url, img);
                        }
                    };
                ]]>
            </script>
            <vbox flex="1" width="400 px">
                <grid>
                    <columns>
                        <column/>
                        <column flex="1"/>
                    </columns>
                    <rows>
                        <row align="center">
                            <label value="Bookmark Title"/>
                            <textbox id="nametb" flex="1" value="document.popupNode.label"/>
                        </row>
                        <row align="center">
                            <label value="Bookmark URL"/>
                            <textbox id="urltb" flex="1" value="document.popupNode.value"/>
                        </row>
                        <row align="center">
                            <label value="Icon URL"/>
                            <textbox id="imgtb" flex="1" value="document.popupNode.image"/>
                        </row>
                    </rows>
                </grid>
            </vbox>
        </dialog>
    </>;
    window. openDialog ("data:application/vnd.mozilla.xul+xml," + dialog. toXMLString (), "", "chrome,dependent,minimizable,resizable=yes,centerscreen,dialog=yes", callback);
    XML. ignoreProcessingInstructions = ipi;
};

I trying to get info from a menu item to appear into the textboxes when the vbox opens

Like document.popupNode.value I can place that into a alert(document.popupNode.value) and it will show the url of the menu item I selected.

yet I not read anywhere where that code/string can be added. 

Does anyone know of a good site on what all what can be added to textbox? 
<label value=""/>
<textbox id="" flex="1" />

*Please no worthless MDN links*