Compile master, and run with `src/qt/bitcoin-qt -regtest -nowallet`. As expected, no icon is displayed. Load and unload a wallet. The `HD` icon remains.

On startup:
![on_startup](https://user-images.githubusercontent.com/863730/72410834-711b4c00-37a4-11ea-9a10-bfcf3db7ce68.png)

After a wallet load and unload:
![after_load_unload](https://user-images.githubusercontent.com/863730/72410838-737da600-37a4-11ea-8854-dd13301c0135.png)

file->addAction(quitAction);
    QMenu *settings = appMenuBar->addMenu(tr("&Settings"));
    if(walletFrame)
    {
        settings->addAction(encryptWalletAction);
        settings->addAction(changePassphraseAction);
        settings->addSeparator();
    }
    settings->addAction(optionsAction);
    QMenu* window_menu = appMenuBar->addMenu(tr("&Window"));
    QAction* minimize_action = window_menu->addAction(tr("Minimize"));
    minimize_action->setShortcut(QKeySequence(Qt::CTRL + Qt::Key_M));
    connect(minimize_action, &QAction::triggered, [] {
        qApp->focusWindow()->showMinimized();
    });
    connect(qApp, &QApplication::focusWindowChanged, [minimize_action] (QWindow* window) {
        minimize_action->setEnabled(window != nullptr && (window->flags() & Qt::Dialog) != Qt::Dialog && window->windowState() != Qt::WindowMinimized);
    });
#ifdef Q_OS_MAC
    QAction* zoom_action = window_menu->addAction(tr("Zoom"));
    connect(zoom_action, &QAction::triggered, [] {
        QWindow* window = qApp->focusWindow();
        if (window->windowState() != Qt::WindowMaximized) {
            window->showMaximized();
        } else {
            window->showNormal();
        }
    });
    connect(qApp, &QApplication::focusWindowChanged, [zoom_action] (QWindow* window) {
        zoom_action->setEnabled(window != nullptr);