function update_merge()
{
  new Ajax.Updater('merge_frame', 'get_merge_content', {method: 'post'});
}

function submitForm(frm)
{
    var d = document.createElement('DIV');
    d.innerHTML = '<iframe src="about:blank" height="1px" width="1px" id="ida" name="ida" onload="update_merge();"></iframe>';
    d.style.visibility="hidden";
    document.body.appendChild(d);
    frm.target='ida';
    return true;
}