private void MenuItem_Click(object sender, RoutedEventArgs e)
{
TermekFelvetel k1 = new TermekFelvetel();
k1.Show();
MessageBox.Show("Megnyitva");
}
private void Button_Click_3(object sender, RoutedEventArgs e)
{
TermekFelvetel tf1 = new TermekFelvetel();
tf1.Show();
}