GanttView allows you to define the deadline of a task, which indicates the time by which a task must be completed. To specify the task deadline, you can use the Deadline property of the Task class.

If your Finish date time exceeds your Deadline date time, a red indicator will appear next to the task number like the following:

Below code snippet shows how you can set the deadline of a task in GanttView.

//Set the deadline of a task
Task1.Deadline = new DateTime(2021, 06, 7);