[VB.NET] Uso di "If...Is Nothing" nella creazione di controlli

[pietro09]

se ho capito

Private IE As InternetExplorer
    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        If IE Is Nothing Then IE = New InternetExplorer()
        IE.Navigate("http://forum.html.it/forum/showthread.php?s=&threadid=1472576")
        IE.Visible = True
    End Sub

    Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click
        If IE Is Nothing Then IE = New InternetExplorer()
        IE.Navigate("http://www.repubblica.it/")
        IE.Visible = True
    End Sub