Using the DateTimePicker in Google Apps Script, I can have the user choose a date and time, and I can use setTimeZoneOffsetInMins to present a UTC date in the correct time zone.

The problem is that fixed timezones don't obey daylight savings time. I don't know before the user enters the date and time whether they'll be entering a time in EST or EDT, and so the timezone offset is guaranteed to be wrong for about half the year.

Is there a solution?