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)

{
#ifdef Q_OS_MAC
    
    appMenuBar = new QMenuBar();
#else
    
    appMenuBar = menuBar();
#endif
    
    QMenu *file = appMenuBar->addMenu(tr("&File"));
    if(walletFrame)
    {
        file->addAction(m_create_wallet_action);
        file->addAction(m_open_wallet_action);
        file->addAction(m_close_wallet_action);
        file->addSeparator();
        file->addAction(openAction);
        file->addAction(backupWalletAction);
        file->addAction(signMessageAction);
        file->addAction(verifyMessageAction);
        file->addSeparator();
    }