Currently, timezone is global to the whole Highcharts library. It would be great if it would be per chart/instance. We have data sources coming from all around the world and we would like to display data based on their local time, for each data source.

Maybe the easiest solution would be for getTimezoneOffset to get chart instance object as a second argument?

But the cleanest would be to make this per-chart (or even per series) option.