Private Sub TabControl1_SelectedIndexChanged(ByVal sender As TabControl, ByVal _
  e As System.EventArgs) Handles myTabControl.SelectedIndexChanged
        If sender.SelectedTab Is Me.securedTabpage Then
            Dim Login As New TabpageLoginForm
            With Login
                .ShowDialog()
            End With
            If Login.UserVerified Then
                Me.securedTabpage.Controls(0).Visible = True
            Else
                MessageBox.Show("Du kommst hier net rein")
                Me.myTabControl.SelectedTab = Me.unsecuredTabpage
            End If
        End If
End Sub