Noticed this while reviewing #13529, but it's also in master @ 5ba77df. On macOS 10.13.6:

<img width="209" alt="schermafbeelding 2018-08-01 om 16 22 09" src="https://user-images.githubusercontent.com/10217/43527498-0f571db4-95a7-11e8-8d90-7863947a7689.png">


<img width="178" alt="schermafbeelding 2018-08-01 om 16 12 51" src="https://user-images.githubusercontent.com/10217/43526994-c9a515ec-95a5-11e8-96b8-9e2513e9aac5.png">

* `Show` in the action menu doesn't work if the app was hidden by `Command + H`, it does work when hidden through this menu
* send and receive don't unhide the window when opened for the action menu. It does navigate to the right tab. The other actions do work (sign, verify & debug window)

Clicking "Toon" (= macOS native show) does work, suggesting the GUI uses some non-native method of hiding.
return;
            }
            progressBarLabel->setText(tr("Connecting to peers..."));
            break;
    }
    QString tooltip;
    QDateTime currentDate = QDateTime::currentDateTime();
    qint64 secs = blockDate.secsTo(currentDate);
    tooltip = tr("Processed %n block(s) of transaction history.", "", count);
    
    if(secs < 90*60)
    {
        tooltip = tr("Up to date") + QString(".<br>") + tooltip;
        labelBlocksIcon->setPixmap(platformStyle->SingleColorIcon(":/icons/synced").pixmap(STATUSBAR_ICONSIZE, STATUSBAR_ICONSIZE));
#ifdef ENABLE_WALLET
        if(walletFrame)
        {
            walletFrame->showOutOfSyncWarning(false);
            modalOverlay->showHide(true, true);
        }
#endif 
        progressBarLabel->setVisible(false);
        progressBar->setVisible(false);
    }
    else
    {
        QString timeBehindText = GUIUtil::formatNiceTimeOffset(secs);
        progressBarLabel->setVisible(true);
        progressBar->setFormat(tr("%1 behind").arg(timeBehindText));
        progressBar->setMaximum(1000000000);