I thought about this quite a bit when working on T117782. I feel that the current CapsuleMultiselectWidget is unsalvageable, it seemed very difficult to reconcile a sensible API for a multiselect widget with allowing the user to add new options at will and using the dropdown menu as the master list of available ones.

If anyone plans to work on this, I'd suggest:

1. Scrap the current CapsuleMultiselectWidget/CapsuleItemWidget entirely, except for the styling
2. Implement two new pairs of classes:
   • CapsuleGroupWidget/CapsuleWidget, which would allow users to insert arbitrary options, and which would support the fancy popup things
   • CapsuleMultiselectWidget/CapsuleMultioptionWidget, which would allow users to select some predefined options from many

@matmarex @Mooeypoo Is this something you want to consider for TagMultiselectWidget or should we decline this task?

This came up before the design and implementation of TagMultiselectWidget and MenuTagMultiselectWidget, which are more or less answering the basic request. Unless there's an additional request here, I think we can close this task as either declined or completed.