Using a Bitcoin-Qt v0.16.0 ([downloaded from bitcoin page](https://bitcoin.org/bin/bitcoin-core-0.16.0/bitcoin-0.16.0-osx.dmg)) in an macOS High Sierra 10.13.4 

When I start after a fresh install Bitcoin-Qt as a mainnet node and wallet, the wallet prompt that about 203gb is going to be used in my disk
![image](https://user-images.githubusercontent.com/20187136/39899688-ba820bfe-5493-11e8-87d9-460ed5716a02.png)

When I start the node and wallet as testnet, shows the same message about the 203gb disk usage
![image](https://user-images.githubusercontent.com/20187136/39899756-17b31214-5494-11e8-8a57-60e604e74afb.png)

It seems that the second time the message is wrong, due that the testnet database uses about 14gb.
case FreespaceChecker::ST_ERROR:
        ui->errorMessage->setText(tr("Error") + ": " + message);
        ui->errorMessage->setStyleSheet("QLabel { color: #800000 }");
        break;
    }
    
    if(status == FreespaceChecker::ST_ERROR)
    {
        ui->freeSpace->setText("");
    } else {
        QString freeString = tr("%n GB of free space available", "", bytesAvailable/GB_BYTES);
        if(bytesAvailable < requiredSpace * GB_BYTES)
        {
            freeString += " " + tr("(of %n GB needed)", "", requiredSpace);
            ui->freeSpace->setStyleSheet("QLabel { color: #800000 }");
        } else {
            ui->freeSpace->setStyleSheet("");
        }
        ui->freeSpace->setText(freeString + ".");
    }
    
    ui->buttonBox->button(QDialogButtonBox::Ok)->setEnabled(status != FreespaceChecker::ST_ERROR);
}
void Intro::on_dataDirectory_textChanged(const QString &dataDirStr)
{
    
    ui->buttonBox->button(QDialogButtonBox::Ok)->setEnabled(false);
    checkPath(dataDirStr);
}
void Intro::on_ellipsisButton_clicked()