Noticed this while reviewing #13529, but it's also in master @ 5ba77df. On macOS 10.13.6:

<img width="209" alt="schermafbeelding 2018-08-01 om 16 22 09" src="https://user-images.githubusercontent.com/10217/43527498-0f571db4-95a7-11e8-8d90-7863947a7689.png">


<img width="178" alt="schermafbeelding 2018-08-01 om 16 12 51" src="https://user-images.githubusercontent.com/10217/43526994-c9a515ec-95a5-11e8-96b8-9e2513e9aac5.png">

* `Show` in the action menu doesn't work if the app was hidden by `Command + H`, it does work when hidden through this menu
* send and receive don't unhide the window when opened for the action menu. It does navigate to the right tab. The other actions do work (sign, verify & debug window)

Clicking "Toon" (= macOS native show) does work, suggesting the GUI uses some non-native method of hiding.
if (strList.size())
        return strList.join(" & ");
    else
        return QObject::tr("None");
}
QString formatPingTime(double dPingTime)
{
    return (dPingTime == std::numeric_limits<int64_t>::max()/1e6 || dPingTime == 0) ? QObject::tr("N/A") : QString(QObject::tr("%1 ms")).arg(QString::number((int)(dPingTime * 1000), 10));
}
QString formatTimeOffset(int64_t nTimeOffset)
{
  return QString(QObject::tr("%1 s")).arg(QString::number((int)nTimeOffset, 10));
}
QString formatNiceTimeOffset(qint64 secs)
{
    
    QString timeBehindText;
    const int HOUR_IN_SECONDS = 60*60;
    const int DAY_IN_SECONDS = 24*60*60;
    const int WEEK_IN_SECONDS = 7*24*60*60;
    const int YEAR_IN_SECONDS = 31556952; 
    if(secs < 60)
    {
        timeBehindText = QObject::tr("%n second(s)","",secs);
    }
    else if(secs < 2*HOUR_IN_SECONDS)
    {
        timeBehindText = QObject::tr("%n minute(s)","",secs/60);
    }
    else if(secs < 2*DAY_IN_SECONDS)