Widgets overview

This is an overview of essentials to resolve for a first public version of the widgets:

Selected

• Implement scipp/ess#138.
• Implement optional parameters. scipp/ess#131
• Implement scipp/ess#140.
• scipp/ess#129
• Show outputs using a vertical layout of checkboxes (instead of list, avoids need to use shift or ctrl ubttons)?
• Show extended outputs as combo-box, so they are mostly hidden by default
• Fix some UI logic around enabling/disabling buttons, make sure things can be run again, ...
• Implement mappable widget wrapping arbitrary other widgets, where rows can be added/removed, yielding a tuple of parameter values. Probably add a mappable field to class Parameter to enable this.
• Low hanging fruit for look&feel: Type formatting, description display, ...
• Split out workflow&output selection to its own widget, make it displayable in a tab (param settings should be in second tab).
• Helper functions to create widgets, instead of creating a single one in the module (some notebooks will need to create multiple workflow widgets). scipp/ess#133
• Parameter that can take existing Python object as input. The widget should parse the global namespace (maybe similar to https://github.com/scipp/scipp/edit/main/src/scipp/object_list.py?), providing a drop-down list of objects to select from. May be filtered by type.
• scipp/ess#108
• Add tests

Needs more thought

• How to select files on the server using a FilenameWidget?
• Consider scipp/ess#135.

Start with the unchecked items in this overview and the linked issues, especially scipp/ess#129 and scipp/ess#135. The payload mentions widgets, FilenameWidget, class Parameter, and scipp/object_list.py; review those entry points and existing tests before choosing one scope. Done would require completing and testing a clearly selected widget improvement, rather than the whole overview.