Right now our handling can be very confusing for editors in an international setting. Our DateTime editor doesn’t present you with timezones, they just do not exist. Instead the DateTime is adjusted and thought of to be in your browsers timezone. This might actually lead to unplanned (content) changes in that an editor in another timezone might change a datetime to something it was not supposed to be.
Now a possible solution would be the following:
The DateTime editor allows setting the timezone (we already save it in the properties JSON anyway). DateTimes are no longer adapted to your browser but are a “fixed” value with the timezone. You should be able to configure a default timezone for the property. For backwards compatibility the adapting to your browser behaviour could be switchable and default to on until next major with the strong suggestion to configure it in the way you want per project so you are upgrade safe. Future extensions could see default timezone per editor if that is required.
In the end this should be way less confusing and give integrators (and editors) more options to work with DateTimes.
Did I forget anything crucial in this plan?