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.
progressBar->setValue(nVerificationProgress * 1000000000.0 + 0.5);
        progressBar->setVisible(true);
        tooltip = tr("Catching up...") + QString("<br>") + tooltip;
        if(count != prevBlocks)
        {
            labelBlocksIcon->setPixmap(platformStyle->SingleColorIcon(QString(
                ":/movies/spinner-%1").arg(spinnerFrame, 3, 10, QChar('0')))
                .pixmap(STATUSBAR_ICONSIZE, STATUSBAR_ICONSIZE));
            spinnerFrame = (spinnerFrame + 1) % SPINNER_FRAMES;
        }
        prevBlocks = count;
#ifdef ENABLE_WALLET
        if(walletFrame)
        {
            walletFrame->showOutOfSyncWarning(true);
            modalOverlay->showHide();
        }
#endif 
        tooltip += QString("<br>");
        tooltip += tr("Last received block was generated %1 ago.").arg(timeBehindText);
        tooltip += QString("<br>");
        tooltip += tr("Transactions after this will not yet be visible.");
    }
    
    tooltip = QString("<nobr>") + tooltip + QString("</nobr>");
    labelBlocksIcon->setToolTip(tooltip);
    progressBarLabel->setToolTip(tooltip);
    progressBar->setToolTip(tooltip);
}
void BitcoinGUI::message(const QString &title, const QString &message, unsigned int style, bool *ret)