The Qt Quick Demo - Clocks uses hard-coded fixed offsets from UTC for the various cities it demonstrates. As a result, it is wrong half the time. It should use the actual time-zone names (which, in most cases, are just the same city names but with a continent prefix, e.g. Europe/London) so that the underlying date-time code can supply the correct time for each city, by passing that zone name to QTimeZone.

Source code is at qtdoc/examples/demos/clocks/
For the cities listed in its clocks.qml, the relevant zones are:

• America/New_York
• Europe/London
• Europe/Oslo
• Asia/Kolkata for Mumbai
• Asia/Tokyo
• Australia/Brisbane
• America/Los_Angeles