function onProgressChanged(sender, eventArgs) {

    var gb = sender.get_element().content.findName("gradB");
    var gc = sender.get_element().content.findName("gradC");
    gc.Offset =1- eventArgs.get_progress()-0.001;
    gb.Offset = 1-eventArgs.get_progress();
    var sltPorciento = sender.get_element().content.findName("txtPorcent");
    sltPorciento.Text = Math.floor(eventArgs.get_progress() * 100) + '%';
    var cnvCenter = sender.get_element().content.findName("cnvCenter");
    var w = document.body.offsetWidth;
    var h = document.body.offsetHeight;
    cnvCenter["Canvas.Left"] = w / 2;
    cnvCenter["Canvas.Top"] = h / 2;
    

}