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.
{
    updateNetworkState();
}
void BitcoinGUI::setNetworkActive(bool networkActive)
{
    updateNetworkState();
}
void BitcoinGUI::updateHeadersSyncProgressLabel()
{
    int64_t headersTipTime = clientModel->getHeaderTipTime();
    int headersTipHeight = clientModel->getHeaderTipHeight();
    int estHeadersLeft = (GetTime() - headersTipTime) / Params().GetConsensus().nPowTargetSpacing;
    if (estHeadersLeft > HEADER_HEIGHT_DELTA_SYNC)
        progressBarLabel->setText(tr("Syncing Headers (%1%)...").arg(QString::number(100.0 / (headersTipHeight+estHeadersLeft)*headersTipHeight, 'f', 1)));
}
void BitcoinGUI::openOptionsDialogWithTab(OptionsDialog::Tab tab)