https://github.com/bitcoin/bitcoin/blob/5180a86c96bc05d2a731f70f36aae28ab5a3fad4/src/qt/sendcoinsdialog.cpp#L339

I think this is %1, not %2
{
    QSettings settings;
    settings.setValue("fFeeSectionMinimized", fFeeMinimized);
    settings.setValue("nFeeRadio", ui->groupFee->checkedId());
    settings.setValue("nConfTarget", getConfTargetForIndex(ui->confTargetSelector->currentIndex()));
    settings.setValue("nTransactionFee", (qint64)ui->customFee->value());
    settings.setValue("fPayOnlyMinFee", ui->checkBoxMinimumFee->isChecked());
    delete ui;
}
void SendCoinsDialog::on_sendButton_clicked()