[Greasemonkey] Javascript character encoding problem

[Jonas Lundberg]

Although this must be a common question, I have not found a good answer to it.

I am posting a form through GM_xmlhttpRequest:

GM_xmlhttpRequest({
    function send(data)             {
    GM_xmlhttpRequest({
    method: 'POST',
    url: mysubmit,
    headers: {
        'Content-type': 'multipart/form-data; boundary=shapecms',
    },
    data: data,
    onload: function(responseDetails) {
            var ok = '200';
            if(responseDetails.status == ok) {
            }
    //       GM_log(responseDetails.responseText);
           load(myfrontpath, 'front');
           notLoadedFront = 'false';
    }
}) };

However, Swedish characters in the "data" variable, are scrambled.
If I look at the data being sent, using the LiveHTTP headers
extension, using a normal submit button all is well:

-----------------------------41184676334
Content-Disposition: form-data; name="titel"

öö
-----------------------------41184676334

However, with GM_xmlhttpRequest I instead get:

-----------------------------41184676334
Content-Disposition: form-data; name="titel"

öö
-----------------------------41184676334


That's not good. What am going wrong here?
I have to use an Ajax call to send the form, because the form is part
of a web sticky notes application (open source), for injecting
discussion forums on web pages.

Regards
Hans