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.
}
    
    if (!msgType.isEmpty())
        strTitle += " - " + msgType;
    
    if (style & CClientUIInterface::ICON_ERROR) {
        nMBoxIcon = QMessageBox::Critical;
        nNotifyIcon = Notificator::Critical;
    }
    else if (style & CClientUIInterface::ICON_WARNING) {
        nMBoxIcon = QMessageBox::Warning;
        nNotifyIcon = Notificator::Warning;
    }
    
    if (style & CClientUIInterface::MODAL) {
        
        QMessageBox::StandardButton buttons;
        if (!(buttons = (QMessageBox::StandardButton)(style & CClientUIInterface::BTN_MASK)))
            buttons = QMessageBox::Ok;
        showNormalIfMinimized();
        QMessageBox mBox(static_cast<QMessageBox::Icon>(nMBoxIcon), strTitle, message, buttons, this);
        mBox.setTextFormat(Qt::PlainText);
        int r = mBox.exec();
        if (ret != nullptr)
            *ret = r == QMessageBox::Ok;
    }
    else
        notificator->notify(static_cast<Notificator::Class>(nNotifyIcon), strTitle, message);
}
void BitcoinGUI::changeEvent(QEvent *e)