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.
{
#ifndef Q_OS_MAC
    
    if (!trayIcon)
        return;
    trayIconMenu = new QMenu(this);
    trayIcon->setContextMenu(trayIconMenu);
    connect(trayIcon, &QSystemTrayIcon::activated, this, &BitcoinGUI::trayIconActivated);
#else
    
    MacDockIconHandler *dockIconHandler = MacDockIconHandler::instance();
    connect(dockIconHandler, &MacDockIconHandler::dockIconClicked, this, &BitcoinGUI::macosDockIconActivated);
    trayIconMenu = new QMenu(this);
    trayIconMenu->setAsDockMenu();
#endif
    
#ifndef Q_OS_MAC
    
    trayIconMenu->addAction(toggleHideAction);
    trayIconMenu->addSeparator();
#endif
    if (enableWallet) {
        trayIconMenu->addAction(sendCoinsMenuAction);
        trayIconMenu->addAction(receiveCoinsMenuAction);
        trayIconMenu->addSeparator();
        trayIconMenu->addAction(signMessageAction);
        trayIconMenu->addAction(verifyMessageAction);