Public Class Form1
    Private WithEvents t As New Timer
    Dim draw As Boolean
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        PictureBox1.SetBounds(5, 5, 270, 270)
        t.Interval = 1000
        t.Start()
    End Sub
 
    Private Sub PictureBox1_Paint(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.PaintEventArgs) Handles PictureBox1.Paint
        For i As Int32 = 0 To 7
            If draw AndAlso (i = 0 OrElse i = 7) Then Continue For
            e.Graphics.FillRectangle(Brushes.Blue, i * 25, i * 25, 70, 70)
            e.Graphics.DrawRectangle(Pens.White, i * 25, i * 25, 70, 70)
        Next
    End Sub
 
    Private Sub t_Tick(ByVal sender As Object, ByVal e As System.EventArgs) _
      Handles t.Tick
        PictureBox1.Refresh()
        draw = Not draw
    End Sub
End Class