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.
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] {
        openOptionsDialogWithTab(OptionsDialog::TAB_NETWORK);
    });
    modalOverlay = new ModalOverlay(this->centralWidget());
#ifdef ENABLE_WALLET
    if(enableWallet) {
        connect(walletFrame, &WalletFrame::requestedSyncWarningInfo, this, &BitcoinGUI::showModalOverlay);
        connect(labelBlocksIcon, &GUIUtil::ClickableLabel::clicked, this, &BitcoinGUI::showModalOverlay);
        connect(progressBar, &GUIUtil::ClickableProgressBar::clicked, this, &BitcoinGUI::showModalOverlay);
    }
#endif
}
BitcoinGUI::~BitcoinGUI()