Gantt chart, aka strip chart, is a popular solution for plans creation and management. You can display any workflow group as a Gantt chart in OneBox OS and manage the tasks: change their deadlines right on the chart, change the priority, order and subordinance.
Technical aspect: Gantt chart is targeted at "planned" field in the orders. By changing this date - the chart blocks positions will be shifted. By dragging the blocks, you change the "planned" date for the task therefore.