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.
{
    this->clientModel = _clientModel;
    if(_clientModel)
    {
        
        
        createTrayIconMenu();
        
        updateNetworkState();
        connect(_clientModel, &ClientModel::numConnectionsChanged, this, &BitcoinGUI::setNumConnections);
        connect(_clientModel, &ClientModel::networkActiveChanged, this, &BitcoinGUI::setNetworkActive);
        modalOverlay->setKnownBestHeight(_clientModel->getHeaderTipHeight(), QDateTime::fromTime_t(_clientModel->getHeaderTipTime()));
        setNumBlocks(m_node.getNumBlocks(), QDateTime::fromTime_t(m_node.getLastBlockTime()), m_node.getVerificationProgress(), false);
        connect(_clientModel, &ClientModel::numBlocksChanged, this, &BitcoinGUI::setNumBlocks);
        
        connect(_clientModel, &ClientModel::message, [this](const QString &title, const QString &message, unsigned int style){
            this->message(title, message, style);
        });
        
        connect(_clientModel, &ClientModel::showProgress, this, &BitcoinGUI::showProgress);
        rpcConsole->setClientModel(_clientModel);
        updateProxyIcon();
#ifdef ENABLE_WALLET
        if(walletFrame)
        {
            walletFrame->setClientModel(_clientModel);
        }
#endif