Private points As New ArrayList
    Private draw As Boolean
 
    Private Sub PictureBox1_MouseUp(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseUp
        points.Add(New Point(e.X, e.Y))
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        draw = True
        Me.Refresh()
    End Sub
 
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button2.Click
        points.Clear()
        draw = False
        Me.Refresh()
    End Sub
 
    Private Sub PictureBox1_Paint(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.PaintEventArgs) Handles PictureBox1.Paint
        For Each p As Point In points
            e.Graphics.DrawEllipse(Pens.Red, p.X - 2, p.Y - 2, 4, 4)
        Next
    End Sub

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