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)

{
    overviewAction->setEnabled(enabled);
    sendCoinsAction->setEnabled(enabled);
    sendCoinsMenuAction->setEnabled(enabled);
    receiveCoinsAction->setEnabled(enabled);
    receiveCoinsMenuAction->setEnabled(enabled);
    historyAction->setEnabled(enabled);
    encryptWalletAction->setEnabled(enabled);
    backupWalletAction->setEnabled(enabled);
    changePassphraseAction->setEnabled(enabled);
    signMessageAction->setEnabled(enabled);
    verifyMessageAction->setEnabled(enabled);
    usedSendingAddressesAction->setEnabled(enabled);
    usedReceivingAddressesAction->setEnabled(enabled);
    openAction->setEnabled(enabled);
    m_close_wallet_action->setEnabled(enabled);
}
void BitcoinGUI::createTrayIcon()
{
    assert(QSystemTrayIcon::isSystemTrayAvailable());
#ifndef Q_OS_MAC
    if (QSystemTrayIcon::isSystemTrayAvailable()) {
        trayIcon = new QSystemTrayIcon(m_network_style->getTrayAndWindowIcon(), this);
        QString toolTip = tr("%1 client").arg(PACKAGE_NAME) + " " + m_network_style->getTitleAddText();
        trayIcon->setToolTip(toolTip);
    }
#endif
}
void BitcoinGUI::createTrayIconMenu()