public bool ParametersAreaVisible { get; set; }

Public Property ParametersAreaVisible As Boolean
	Get
	Set

// Toggle the parameters area
private void button10_Click(object sender, System.EventArgs e)
{
    this.ReportViewer1.ParametersAreaVisible = !this.ReportViewer1.ParametersAreaVisible;
}

' Toggle the parameters area
Private Sub button10_Click(sender As Object, e As System.EventArgs)
    Me.ReportViewer1.ParametersAreaVisible = Not Me.ReportViewer1.ParametersAreaVisible
End Sub