Private Sub btn_kunden_Click(ByVal sender As Object, ByVal e As _
  System.EventArgs) Handles btn_kunden.Click
 
    Using frm As New frm_kundenstamm("Kunde auswählen")
 
        if frm.ShowDialog() == DialogResult.OK Then
            txt_adresse.AppendText(frm.AdressText)
        End If
 
    End Using
 
End Sub

Public Property AdressText as String
 
Private Sub list_kunden_DoubleClick(ByVal sender As Object, ByVal e As _
  System.EventArgs) Handles list_kunden.DoubleClick
 
    If Me.Text = "Kunde auswählen" Then
 
        AdressText = kundentext_aus_db_fuellen( Convert.ToInt32( _
          l_kundennr.Text))
        DialogResult = DialogResult.OK
    End If
 
End Sub