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)

{
    QMainWindow::changeEvent(e);
#ifndef Q_OS_MAC 
    if(e->type() == QEvent::WindowStateChange)
    {
        if(clientModel && clientModel->getOptionsModel() && clientModel->getOptionsModel()->getMinimizeToTray())
        {
            QWindowStateChangeEvent *wsevt = static_cast<QWindowStateChangeEvent*>(e);
            if(!(wsevt->oldState() & Qt::WindowMinimized) && isMinimized())
            {
                QTimer::singleShot(0, this, &BitcoinGUI::hide);
                e->ignore();
            }
            else if((wsevt->oldState() & Qt::WindowMinimized) && !isMinimized())
            {
                QTimer::singleShot(0, this, &BitcoinGUI::show);
                e->ignore();
            }
        }
    }
#endif
}
void BitcoinGUI::closeEvent(QCloseEvent *event)