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
{
    if(!clientModel)
        return;
    if (!isHidden() && !isMinimized() && !GUIUtil::isObscured(this) && fToggleHidden) {
        hide();
    } else {
        GUIUtil::bringToFront(this);
    }
}
void BitcoinGUI::toggleHidden()
{
    showNormalIfMinimized(true);
}
void BitcoinGUI::detectShutdown()
{
    if (m_node.shutdownRequested())
    {
        if(rpcConsole)
            rpcConsole->hide();
        qApp->quit();
    }
}
void BitcoinGUI::showProgress(const QString &title, int nProgress)