The method Dates.getTimezoneOffset is not working properly for some dates.
This leads to incorrect display of such dates in the components Datebox and Timebox.
For example for birth date (dd.mm.yyyy) 11.10.1978 for timezone "Europe/Moscow":

GregorianCalendar testGregorianCalendar = new GregorianCalendar();
testGregorianCalendar.set(Calendar.DAY_OF_MONTH, 11);
testGregorianCalendar.set(Calendar.MONTH, 9);
testGregorianCalendar.set(Calendar.YEAR, 1978);
testGregorianCalendar.set(Calendar.HOUR_OF_DAY, 0);
testGregorianCalendar.set(Calendar.MINUTE, 12);

Date date = new Date(testGregorianCalendar.getTimeInMillis());

System.out.println("Dates.getTimezoneOffset|" + Dates.getTimezoneOffset(TimeZone.getTimeZone("Europe/Moscow"), date));
System.out.println("TimeZone.getTimeZone(\"Europe/Moscow\").getOffset|" + TimeZone.getTimeZone("Europe/Moscow").getOffset(date.getTime()));

Output:

Dates.getTimezoneOffset|14400000 // 4 hours - INCORRECT - in 1978 in "Europe/Moscow" offset WAS 3 hours (4 hours is current offset not in 1978)
TimeZone.getTimeZone("Europe/Moscow").getOffset|10800000 // 3 hours - CORRECT - in 1978 in "Europe/Moscow" offset WAS 3 hours

This leads to incorrect display of such dates in the components Datebox and Timebox if TimeZones.getCurrent() is not equal timezone of the component.
11.10.1978 00:12 displayed as 10.10.1978 (date - from code above; TimeZones.getCurrent() is "Europe/Moscow"):

birthdateDatebox1.setTimeZone(TimeZone.getTimeZone("GMT"));
birthdateDatebox1.setValue(date);