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)

{
    
    if(event->mimeData()->hasUrls())
        event->acceptProposedAction();
}
void BitcoinGUI::dropEvent(QDropEvent *event)
{
    if(event->mimeData()->hasUrls())
    {
        for (const QUrl &uri : event->mimeData()->urls())
        {
            Q_EMIT receivedURI(uri.toString());
        }
    }
    event->acceptProposedAction();
}
bool BitcoinGUI::eventFilter(QObject *object, QEvent *event)