contenteditable not working in xul window

Hello everybody,

I have a xul runner applications and at a certain moment I have use
several html editors. I was thinking that it is much easier to write +
handle  something like

<html:div contenteditable="true">some content to be edited</html:div>

rather than <xul:editor>, etc. This works very well into an xhtml
document, but into a xul one, the editable div gets focus and the dotted
border, but remains read-only. Am I missing something or there is a bug?
Or this is the intended behavior? In any case, I am finding this feature
very useful because in my case not only simplifies my life, but, I think
it reduces the load.


If you want to try, you can use this simple example:

<?xml version="1.0"?>
<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
<window 
xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
         xmlns:html="http://www.w3.org/1999/xhtml">

    <box>
     <html:div contenteditable="true">some content</html:div>
    </box>

</window>


I am using xul runner 1.9.1.3, but the same happens in ff 3.6

thanks for help