Clobbered class names in ClassSelector.get_range

[maximlt]

We found out that classes with the same name (e.g. in different files) get clobbered in concrete_descendents. We extended descendents with a concrete parameter, and added a warning in concrete_descendents (#1035).

We have a problem with ClassSelector.get_range, where classes with the same name are still clobbered. Options include:

• Updating somehow the returned type to a list of tuples
• Creating another method like range that doesn't suffer from this problem
• Returning a MultiDict
• etc.

A couple of difficulties with get_range:

• It's implemented by other Selector subclasses, so I guess their return type should be identical, or at least behave the same way
• It's used quite a bit internally by Panel at least (maybe more, to be checked)

So this needs a nice transition plan.