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.
QAction* backupWalletAction = nullptr;
    QAction* changePassphraseAction = nullptr;
    QAction* aboutQtAction = nullptr;
    QAction* openRPCConsoleAction = nullptr;
    QAction* openAction = nullptr;
    QAction* showHelpMessageAction = nullptr;
    QAction* m_wallet_selector_label_action = nullptr;
    QAction* m_wallet_selector_action = nullptr;
    QLabel *m_wallet_selector_label = nullptr;
    QComboBox* m_wallet_selector = nullptr;
    QSystemTrayIcon* trayIcon = nullptr;
    QMenu* trayIconMenu = nullptr;
    Notificator* notificator = nullptr;
    RPCConsole* rpcConsole = nullptr;
    HelpMessageDialog* helpMessageDialog = nullptr;
    ModalOverlay* modalOverlay = nullptr;
    
    int prevBlocks = 0;
    int spinnerFrame = 0;
    const PlatformStyle *platformStyle;
    
    void createActions();
    
    void createMenuBar();
    
    void createToolBars();
    
    void createTrayIcon(const NetworkStyle *networkStyle);
    
    void createTrayIconMenu();