@(Html.Kendo().Gantt<TaskViewModel, DependencyViewModel>()
    .Name("gantt")
    ...
    .DataSource(ds => ds
      ...
      .Events(ev => ev.Change("onDSChange"))
  )
)

<script>
function onDSChange(e) {
  var sortedFields = e.sender.sort();
  if(sortedFields.length > 0) { //The GanttList is sorted
    ...
  }
}
</script>