#3469442: Impossible to drop a component into an empty column of the two

Closes #3469442

components/containers/two_column/two_column.component.yml

@@ -17,14 +17,10 @@ slots:
   column_one:
     title: Column One
     description: The contents of the first column.
-    # @todo can_be_dropzone: true
     examples:
       - <p>This is column 1 content</p>
-    # @todo this should be a dropzone
   column_two:
     title: Column Two
     description: The contents of the second column.
-    # @todo can_be_dropzone: true
     examples:
       - <p>This is column 2 content</p>
-    # @todo this should be a dropzone

[Ted Bowman]

Maybe in follow-up but it would be good to have test coverage at least in phpunit that if you saved a node using the field_xb_demo with nothing in 2nd column that this would be rendered. I know we have test coverage in ComponentTreeHydratedTest but this would seem more real world. either that in the Cypress E2E

[Wim Leers]

Detailed E2E tests for dropzones might be worth it in the future, yes. But most of the complexity is on the server side, so I think this is sufficient to land as-is. It definitely is crucial for the 0.1.0 demo at Barcelona.