If the main window has been minimized to the taskbar (iconified) calling "Show/Hide", "Send" or "Receive" actions from the tray icon menu has no effect: the main window still minimized.

It seems like a Qt bug similar to that old [one](https://bugreports.qt.io/browse/QTBUG-31117).

Tested platform: Linux Mint 19, Qt 5.9.5 / 5.9.6
{
    
    m_handler_message_box = m_node.handleMessageBox(boost::bind(ThreadSafeMessageBox, this, _1, _2, _3));
    m_handler_question = m_node.handleQuestion(boost::bind(ThreadSafeMessageBox, this, _1, _3, _4));
}
void BitcoinGUI::unsubscribeFromCoreSignals()
{
    
    m_handler_message_box->disconnect();
    m_handler_question->disconnect();
}
UnitDisplayStatusBarControl::UnitDisplayStatusBarControl(const PlatformStyle *platformStyle) :
    optionsModel(0),
    menu(0)
{
    createContextMenu();
    setToolTip(tr("Unit to show amounts in. Click to select another unit."));
    QList<BitcoinUnits::Unit> units = BitcoinUnits::availableUnits();
    int max_width = 0;
    const QFontMetrics fm(font());
    for (const BitcoinUnits::Unit unit : units)
    {
        max_width = qMax(max_width, fm.width(BitcoinUnits::longName(unit)));
    }
    setMinimumSize(max_width, 0);
    setAlignment(Qt::AlignRight | Qt::AlignVCenter);
    setStyleSheet(QString("QLabel { color : %1 }").arg(platformStyle->SingleColor().name()));
}
void UnitDisplayStatusBarControl::mousePressEvent(QMouseEvent *event)