Public Class Form1
    Dim Schalter As Boolean = False
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        Dim ReiterKarte(0 To Me.TabControl1.TabPages.Count - 1)
        For i As Integer = 0 To Me.TabControl1.TabPages.Count - 1
            ReiterKarte(i) = Me.TabControl1.TabPages.Item(i)
        Next
 
        For i As Integer = 1 To Me.TabControl1.TabPages.Count - 1
            Me.TabControl1.TabPages.Remove(ReiterKarte(i))
        Next i
    End Sub
 
    Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, _
      ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
        If Schalter = False Then
            Me.TabControl1.TabPages.Add(TabPage2)
            Schalter = True
        End If
    End Sub
End Class