Is it possible to enable a contextMenu similar to taskMenu but with different options when we click below the last task rather than showing the Chrome contextMenu?
It is not configurable but it can be done. The area below the task list is just and HTML element so listener can be installed on it. You can access this element and install listener on it this way:
Gantt needs its own subclass of ScheduleMenu which inherits from Scheduler's. It can be not enabled by default (because I cant think of any default items), but it is most definitely something which our client developers could find uses for.