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.
{
    return date.date().toString(Qt::SystemLocaleShortDate) + QString(" ") + date.toString("hh:mm");
}
QString dateTimeStr(qint64 nTime)
{
    return dateTimeStr(QDateTime::fromTime_t((qint32)nTime));
}
QFont fixedPitchFont()
{
#if QT_VERSION >= 0x50200
    return QFontDatabase::systemFont(QFontDatabase::FixedFont);
#else
    QFont font("Monospace");
    font.setStyleHint(QFont::Monospace);
    return font;
#endif
}
static const uint8_t dummydata[] = {0xeb,0x15,0x23,0x1d,0xfc,0xeb,0x60,0x92,0x58,0x86,0xb6,0x7d,0x06,0x52,0x99,0x92,0x59,0x15,0xae,0xb1,0x72,0xc0,0x66,0x47};
static std::string DummyAddress(const CChainParams &params)