[ismail2012]

هل هذا قصدك
Public Class Form1

    Private Sub Form1_Activated(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Activated
        Form2.Close()
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Form2.Show()
    End Sub
End Class