Noticed this while reviewing #13529, but it's also in master @ 5ba77df15. On macOS 10.13.6:

```
bitcoin-qt -disablewallet
```

<img width="1354" alt="schermafbeelding 2018-08-01 om 16 03 41" src="https://user-images.githubusercontent.com/10217/43526506-b23264d8-95a4-11e8-81a0-5debcad838ae.png">

The usual progress modal doesn't appear when QT starts, and clicking on the progress bar has no effect. It works fine when there's a wallet present.
}
class ModalOverlay : public QWidget
{
    Q_OBJECT
public:
    explicit ModalOverlay(QWidget *parent);
    ~ModalOverlay();
public Q_SLOTS:
    void tipUpdate(int count, const QDateTime& blockDate, double nVerificationProgress);
    void setKnownBestHeight(int count, const QDateTime& blockDate);
    void toggleVisibility();
    
    void showHide(bool hide = false, bool userRequested = false);
    void closeClicked();
    bool isLayerVisible() const { return layerIsVisible; }
protected:
    bool eventFilter(QObject * obj, QEvent * ev);
    bool event(QEvent* ev);
private:
    Ui::ModalOverlay *ui;
    int bestHeaderHeight; 
    QDateTime bestHeaderDate;
    QVector<QPair<qint64, double> > blockProcessTime;
    bool layerIsVisible;
    bool userClosed;
};
#endif