public FlightFilter()
{
InitializeComponent();
using (FlightServiceClient fsc = new FlightServiceClient())
{
foreach (string s in fsc.getCountries())
{
cb_a_land.Items.Add(s);
cb_v_land.Items.Add(s);
}
foreach (string s in fsc.getAirPlaneClasses())
cb_klasse.Items.Add(s);
}
}