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.
namespace interfaces {
    class Node;
}
namespace Ui {
    class Intro;
}
/** Introduction screen (pre-GUI startup).
  Allows the user to choose a data directory,
  in which the wallet and block chain will be stored.
 */
class Intro : public QDialog
{
    Q_OBJECT
public:
    explicit Intro(QWidget *parent = 0);
    ~Intro();
    QString getDataDirectory();
    void setDataDirectory(const QString &dataDir);
    /**
     * Determine data directory. Let the user choose if the current one doesn't exist.
     *
     * @returns true if a data directory was selected, false if the user cancelled the selection
     * dialog.
     *
     * @note do NOT call global GetDataDir() before calling this function, this