// ______________________________________________________________

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

            SetDrawer(drawingBoard);
            _instance = new Instance(_params.Symbols, _params.Samples, _params.PerSymbolSamples);
            InputParams.SetClasses(tableClasses, _params.Symbols, _params.Samples);
            SetButtons();
        }