private void CurrencyComboBox_SelectedIndexChanged(object sender, EventArgs e)
{
if (CurrencyComboBox.SelectedItem != null)
{
currentCurrency = CurrencyComboBox.SelectedItem as CurrencyModel;
ratesChart.Series[0].Name = currentCurrency.currency_name;
FlagPictureBox.Image = currentCurrency.Flag();
}
FlagPictureBox.Focus();
}