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(!clientModel)
        return;
    if (!isHidden() && !isMinimized() && !GUIUtil::isObscured(this) && fToggleHidden) {
        hide();
    } else {
        GUIUtil::bringToFront(this);
    }
}
void BitcoinGUI::toggleHidden()
{
    showNormalIfMinimized(true);
}
void BitcoinGUI::detectShutdown()
{
    if (m_node.shutdownRequested())
    {
        if(rpcConsole)
            rpcConsole->hide();
        qApp->quit();
    }
}
void BitcoinGUI::showProgress(const QString &title, int nProgress)