private void cancelbutton_Click(object sender, EventArgs e)
 {
     // revert to saved values
     _param = _lastsaved;
     _convp = _convp_lastsaved;
     _avp   = _avp_lastsaved;
 }
        private void applybutton_Click(object sender, EventArgs e)
        {
            FPSParameters plocal = new FPSParameters();

            StoreCurrentValues(ref plocal);
            _param[config_comboBox.SelectedItem.ToString()] = plocal;

            // permanently save current values
            _lastsaved       = new Dictionary <string, FPSParameters>(_param);
            _convp_lastsaved = _convp;
            _avp_lastsaved   = _avp;
        }