protected void hdnButtonUrl_Click(object sender, EventArgs e)
    {
        Hashtable properties = new Hashtable();

        properties[DialogParameters.URL_URL]         = txtUrl.Text.Trim();
        properties[DialogParameters.EDITOR_CLIENTID] = Config.EditorClientID;
        drpMediaType.SelectedValue = "";
        ItemProperties.LoadProperties(properties);
    }