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.
frameBlocksLayout->addStretch();
    frameBlocksLayout->addWidget(labelBlocksIcon);
    frameBlocksLayout->addStretch();
    
    progressBarLabel = new QLabel();
    progressBarLabel->setVisible(false);
    progressBar = new GUIUtil::ProgressBar();
    progressBar->setAlignment(Qt::AlignCenter);
    progressBar->setVisible(false);
    
    
    
    QString curStyle = QApplication::style()->metaObject()->className();
    if(curStyle == "QWindowsStyle" || curStyle == "QWindowsXPStyle")
    {
        progressBar->setStyleSheet("QProgressBar { background-color: #e8e8e8; border: 1px solid grey; border-radius: 7px; padding: 1px; text-align: center; } QProgressBar::chunk { background: QLinearGradient(x1: 0, y1: 0, x2: 1, y2: 0, stop: 0 #FF8000, stop: 1 orange); border-radius: 7px; margin: 0px; }");
    }
    statusBar()->addWidget(progressBarLabel);
    statusBar()->addWidget(progressBar);
    statusBar()->addPermanentWidget(frameBlocks);
    
    this->installEventFilter(this);
    
    setWalletActionsEnabled(false);
    
    subscribeToCoreSignals();
    connect(connectionsControl, &GUIUtil::ClickableLabel::clicked, [this] {
        m_node.setNetworkActive(!m_node.getNetworkActive());
    });
    connect(labelProxyIcon, &GUIUtil::ClickableLabel::clicked, [this] {