There are a few more updates in the works today, specifically sorting.
I believe that a Gantt chart should be a "waterfall" from left to right, with tasks that start earliest at the top left. This leads to:
Workspaces don't have a date, so they should be alphabetical.
Milestones have a due date but no start date, and confusingly their date has nothing to do with the date(s) of constituent tasks or sub-tasks. jsGantt resolves this, however, by setting the start and end date of a milestone to the earliest and latest dates of the constituent tasks. Bear in mind that a milestone in project terms is a single-date achievement, but because we are using milestones to "group" tasks and sub-tasks for our projects in Feng Office, we (and jsGantt) are treating them more like groups or sub-projects than actual milestones.
Tasks and sub-tasks should be sorted by Start Date, End Date, then alphabetically.
That is probably the next version we will be sharing.