feat(ui): collapsible section widget should be a container
Description
Since !1035 (merged), a collapsible widget is available. However, it would be nice if the widget were indeed a container so we can define its content in xml.
Optionally, you may give directions about how to address the issue.
Functional specifications
Workflow, UX/UI design, screenshots, etc...
Technical specifications
Details of the implementation.
Test plan
Describe how you will verify that the implementation meets specifications.