Record which groups are collapsed when calling Taggle.dump()

[jamesscottbrown]

It would be great if the serialization of a Taggle object produced by Taggle.dump() specified which groups were expanded or collapsed.

Currently, if a user Groups rows based on the values in one column, and colapse some (or all) groups, the output of Taggle.dump() does not record which groups were collapsed, so calling Taggle.restore() results in expanding all groups.

This has two consequences:

• calling dump then restore loses an important aspect of the vsualization's state
• it isn't possible to externally control which groups are collapsed by dumping modifying and reloading the state (and I can't see an API to do this directly)