The Blueprint Tree is currently presented with the root container at the top of the hierarchy:

This causes two issues:

• The root container being, by definition, always alone at its level, it causes significant right-ward indentation for not much user benefit.
• Since nothing can be inserted after or before the root container (again, by definition), it behaves somewhat unexpected with the drag and drop introduced in Add support for drag-and-drop in blueprint tree #4910.

In order to acknowledge the fundamental difference between the root container and all other container, and adjust the presentation to highlight that different and address the current shortcoming, we propose the following changes:

1. The root container no longer has the the collapsing triangle and thus cannot be collapsed. This allows left-shifting the entire tree.
2. The root container is named differently than other containers, for example "Viewport (Grid)"/"Viewport (Horizontal)"/etc.
3. The root container is no longer draggable (though it is now draggable, it's impossible to find a suitable target drop anyways).

Appart from these changes, the root container would remain selectable/editable as it currently is (maybe with minor adjustment in the selection panel to acknowledge its difference).

Mock-up: