Is it possible to change the shape (diamond->rectangle) of a concise signal in a timing diagram?

Question

I would like to abuse the timing-diagram to draw a task/thread diagram. It would look a lot cleaner, if it would be possible to change the shape of a concise signal.

The concise signal could represent a task as running, preempted {-}, or finished {hidden}.

Comments

Indeed this would be useful when drawing task diagrams. I have tried to come up with work-around using binary and robust signals but creating a readable task diagram that way turns out to be difficult and the diagram soon becomes unreadable as the number of tasks and time span increases. I also considered abusing concise signal notation but there does not seem to way around the diamond shape which is not good for task swaps especially when the tasks's running time is small compared to width of the diamond.