Private Sub pb_Paint(sender As Object, _
        e As System.Windows.Forms.PaintEventArgs) Handles pb.Paint
 
        Dim txt As String, c As String = " "
 
        If String.IsNullOrEmpty(tb.SelectedText) Or cv Then
            If cv Then
                c = "|" 
            Else
                c = " "
            End If
            txt = tb.Text.Insert(tb.SelectionStart, c)        
        Else
            txt = tb.Text.Substring(0, tb.SelectionStart)
            txt &= New String("_"c, tb.SelectionLength)
            txt &= tb.Text.Substring(tb.SelectionStart + tb.SelectionLength)
        End If
 
        Using br As New SolidBrush(tb.ForeColor)
            e.Graphics.DrawString(txt, tb.Font, br, 0, 0)
        End Using
 
    End Sub