not support realStartDate and realEndDate?

[Aes-Xin]

not support realStartDate and realEndDate?

[gearcoded]

Hello,
Gantt uses the start_date and end_date properties as the date parameters:
https://docs.dhtmlx.com/gantt/desktop__loading.html#dataproperties
You can add the realStartDate and realEndDate as custom properties. Or you can set the start_date and end_date properties from the realStartDate and realEndDate properties.
Here is an example of how it might be implemented:
http://snippet.dhtmlx.com/5/a6e57057a

If you need something different, please, describe your question in more detail.