void MainFieldInverviewMenu_NewFieldInverview() { FieldContactEntry ie = new FieldContactEntry(); TabItem ti = new TabItem(); ti.Header = "New"; ti.Content = ie; ie.Visibility = Visibility.Visible; IncidentTabControl.Items.Add(ti); IncidentTabControl.SelectedItem = ti; ie.Width = Double.NaN; ie.Height = Double.NaN; }