private void comboBoxRegions_SelectedIndexChanged(object sender, EventArgs e)
{
if (this.currentCountries != null)
{
this.listBoxFrequencies.Items.Clear();
List<string> region;
if (this.currentCountries.TryGetValue((string)this.comboBoxRegion.SelectedItem, out region))
foreach (string r in region)
this.listBoxFrequencies.Items.Add(r);
}
}