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.
{
#ifndef Q_OS_MAC 
    if(clientModel && clientModel->getOptionsModel())
    {
        if(!clientModel->getOptionsModel()->getMinimizeOnClose())
        {
            
            rpcConsole->close();
            QApplication::quit();
        }
        else
        {
            QMainWindow::showMinimized();
            event->ignore();
        }
    }
#else
    QMainWindow::closeEvent(event);
#endif
}
void BitcoinGUI::showEvent(QShowEvent *event)