// ______________________________________________________________

        //
        // Parameters panel
        //
        private void ParamsPanel_Visible(object sender, EventArgs e)
        {
            if (!(sender is Panel panel))
            {
                return;
            }
            if (!panel.Visible)
            {
                return;
            }

            InputParams.FillParamChoices(numOfSymbols, numOfSamples, numOfSymbolSamples, loadTestSet);
            buttonLoadTestSet.Enabled = loadTestSet.SelectedItem != null;
        }