in gantt view -- A) drag via two break lines or points at opposite ends of each bar -- or B) the ability to click anywhere on the bar and see one or two anchor points -- for a high level view of a task that has many components or stages before finally complete.
2-stage example: "plan" stage, left from the only anchor point to the start point in diagonal stripes, and "execute" stage, as is, one solid color. Can relate to % complete as well, plan 80%, execute 20%.
3-stage example: "Plan", "build" (execute), "plus "test" stage, right from the second anchor point to the end point, in vertical stripes. 30%-50%-20% splits.