var help_win;
function show_help(url) {
    if (!help_win) {
        help_win = new Ext.Window({
            buttons: [{ handler: function() { help_win.hide(); }, text: 'Stäng'}],
            closeAction: 'hide',
            height: 445,
            items: new Ext.Panel({ autoLoad: { url: url, nocache: true }, autoScroll: true }),
            layout: 'fit',
            plain: true,
            title: 'Hjälp',
            width: 620
        });
    }
    help_win.show();
}