Qt 5.7 QTimeZone::abbreviation()

[ad5xj]

I would like to display the local time zone as an abbreviation similar to CST, CDT, etc. The QTimeZone class returns "Central Daylight Time" for the abbreviation function. This does not seem to be abbreviated at all. I would have expected the common "CDT" abbreviation instead.

Here is the code:

QDateTime curtim = QDateTime::currentDateTime();
    ui->lblCurTime->setText(curtim.toString("hh:mm:ss"));
    mwd->TZ = curtim.timeZone();
    QString abbr = mwd->TZ = curtim.timeZone().abbreviation();
    ui->lblTZ->setText(abbr);

QDateTime curtim = QDateTime::currentDateTime();
    ui->lblCurTime->setText(curtim.toString("hh:mm:ss"));
    mwd->TZ = curtim.timeZone();
    QString abbr = mwd->TZ = curtim.timeZone().abbreviation();
    ui->lblTZ->setText(abbr);

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The output looks like 12:30:30 Central Daylight Time

Environment:
OS: Windows 10 32-bit
Qt: v5.7.1 MinGW 5.3.0 32-bit

Note: Same problem exists on Linux Mint 17.3 32-bit

What am I doing wrong?