Visual indication of last nodes of a tree

When a map is rendered , a visual language does not make it trivial that an item has no sub-items, so user might try to open / close them, @anttisalo any suggestions for a clear indication, which does not take a massive toll on the implementation, color or shape changes, something less taxing then a full new GUI ?

No file, test, or entry point is named in the issue. First review the tree-rendering implementation and the existing comment discussion, then agree on a low-cost visual treatment for leaf nodes and verify that rendered items without sub-items are clearly distinguishable.

Written by the indexing model from the issue text.