private void periodRadioButtons_CheckedChanged(object sender, EventArgs e)
        {
            int period = 365; // default 1 year

            if (sender == rbPeriod10Y)
            {
                period = 3650;
            }
            else if (sender == rbPeriod1Y)
            {
                period = 365;
            }
            else if (sender == rbPeriod9M)
            {
                period = 270;
            }
            else if (sender == rbPeriod6M)
            {
                period = 180;
            }
            else if (sender == rbPeriod3M)
            {
                period = 90;
            }
            else if (sender == rbPeriod1M)
            {
                period = 30;
            }
            else
            {
                period = 365;
            }
            intSelectedPeriod = period;
            Drawing.DrawChart(chrtMain, lstFavorites.Find(x => x.Name == lbFavorites.SelectedItem.ToString()), period);
        }
        private void lbFavorites_SelectedIndexChanged(object sender, EventArgs e)
        {
            ListBox lb = (ListBox)sender;

            Drawing.DrawChart(chrtMain, lstFavorites.Find(x => x.Name == lb.SelectedItem.ToString()), intSelectedPeriod);
        }