The tree drag and drop proposal allows extensions to provide data transfer items when a tree item is dragged, but the only way to drag into the editor is to attach a resource to the tree item.

Attaching a resource to a tree items means that the tree item will receive resource related display characteristics (decorations colors for example). This is not always desirable.

In the existing handleDrag API proposal, we should allow extensions to provide a resourceurls mime type that the editor then knows how to handle when the tree item is dropped there. This resourceurls type is already used internally.