This is related to scipp/sciline#92. So ideally, the solution here can also be used with the JSON repr of Sciline. Even if it is not a complete solution to that issue.

I thought it should be distinct: Saving workflow parameters is different from storing the widget state. As a simple example, the workflow input parameters might be some bin-edges (an "arbitrary" variable), while the widget state gives start, stop, nbin, and scale (lin or log).

But maybe there is a better abstraction?

Yeah, it's not really possible to fill widget inputs from a parameter value from the graph, i.e. scipp.Variable.
Maybe the title was misleading. I'll update it.

There are some widgets that needs explicit handling.

TODO:

• Dropdown widget Find set_fields or value setter. - Handle value setter with try-except instead of a condition #149
• Optional widget (wrapper) - Switch/Optional widget fields setter/getter #148
• Switchable widget (wrapper)