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.
{
    QMainWindow::changeEvent(e);
#ifndef Q_OS_MAC 
    if(e->type() == QEvent::WindowStateChange)
    {
        if(clientModel && clientModel->getOptionsModel() && clientModel->getOptionsModel()->getMinimizeToTray())
        {
            QWindowStateChangeEvent *wsevt = static_cast<QWindowStateChangeEvent*>(e);
            if(!(wsevt->oldState() & Qt::WindowMinimized) && isMinimized())
            {
                QTimer::singleShot(0, this, &BitcoinGUI::hide);
                e->ignore();
            }
            else if((wsevt->oldState() & Qt::WindowMinimized) && !isMinimized())
            {
                QTimer::singleShot(0, this, &BitcoinGUI::show);
                e->ignore();
            }
        }
    }
#endif
}
void BitcoinGUI::closeEvent(QCloseEvent *event)