How does the 'parent' category aggregate tasks? It seems to do a reasonable job picking a min start-date and max end-date ... but everything else seems to just be copied from the first child task rather than perform any kind of sensible aggregation -- and the fields don't accept measures so I can't write my own logic.
If I have a parent "Park Restoration" and two tasks "Trim Trees" and "Build benches" and I have a 'cost' associated with both. When I collaps the gantt I want to see the earliest start and the latest end, and I want show the combined cost in the tooltip. But I can only get the cost from the top task, not the sum of costs of all tasks with the same parent.
