/// <summary>
    /// User has clicked the login button. Sets up a new OpenIDConsumer
    /// object and begins the authentication sequence. 
    /// Fires the OnLogin event. 
    /// </summary>
    /// <param name="sender">Object invoking this method.</param>
    /// <param name="e">EventArgs related to this request.</param>
    protected void Button_Click(object sender, EventArgs e)
    {
        OpenIDConsumer openid = new OpenIDConsumer();
        SetAuthMode(openid);
        SimpleRegistration sr = new SimpleRegistration(openid);
        if (this.RequiredFields != null) { sr.RequiredFields = this.RequiredFields; }
        if (this.OptionalFields != null) { sr.OptionalFields = this.OptionalFields; }
        if (this.PolicyURL != null) { sr.PolicyURL = this.PolicyURL; }
        openid.Identity = openid_url.Text;
        this.Identity = openid.Identity;
        OnLogin(e);
        openid.BeginAuth();

        if (openid.IsError())
        {
            LLabel.Text = openid.GetError();
        }
        else
        {
            LLabel.Text = "";
        }
    }