expander/collapser states not retained; no way to collapse all

Edit Subject

The new expand/collapse functionality is great, but it doesn't remember which ones are collapsed. For example, even if you simply start to create a new backlog item, then cancel it, it refreshes the planning board and all the child items are expanded again. Any action that causes the Planning Board to refresh will cause this. e.g. switching to the Task Board and back.

It would be less of an annoyance if there were a way to collapse all with one click.