Widget Roadmap :
Progress is based on closed, that is to say "not open".
That leads to non-coherent behavior when you have a cancelled status for instance, which is not open, nor done.
If I have one story with 3 tasks, one "ongoing", one "done", one "cancelled". I should have a 50% progress, while I have a 66%.
Then progress should be based on done semantics if set.