CDK Drag and Drop: Nested Drag and Drop does not allow sorting on same level

Reproduction

StackBlitz: https://stackblitz.com/edit/angular-wfrzq9

Steps to reproduce:

1. Switch ‘child a’ and ‘child b’
2. Directly switching a and b will fail

• Workaraound in the example: Drag child b after Parent_2 and drag it again into the list before child a

Expected Behavior

Dragging within the inner cdkDropList should work, the outher cdkDropList should only fire if the element is moved out of its list.

Actual Behavior

The inner cdkDropList does listen to the drag - the outer list is called.

might be caused by components/src/cdk/drag-drop/directives/drop-list.ts 304: ref.connectedTo(siblings.filter(drop => drop && drop !== this).map(list => list._dropListRef))

Environment

• Angular: 9.0.0
• CDK/Material: 9.0.0
• Browser(s): Chrome 80.0.3987.87
• Operating System (e.g. Windows, macOS, Ubuntu): Win 10

[crisbeto]

I spent a bit of time on this, but it looks like it’ll be tricky if we want to cover all the cases. I have a solution that somewhat works here, but there are definitely edge cases that it won’t cover.

[angular-automatic-lock-bot[bot]]

This issue has been automatically locked due to inactivity. Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}