It would be nice if tasks could be added to gantt that are missing a start date, end date or both dates. For our use case this feature is not only useful, but mandatory. We are visualising a project workflow that goes through several phases and steps. Within our application, the client fills in the dates for these tasks and milestones as the project progresses. Not all dates are filled-in at all times, however when a project manager creates a gantt chart, he wants to see all the tasks. A task without a date is an information in itself. Currently we have to create a fake date entry for tasks without dates.