What new or enhanced feature are you proposing?

Add tooltip to a node icon and not only to the node text something like

node.data.iconTooltip = "This node has extra data";

What goal would this enhancement help you achieve?

Would let me put a tooltip for each difference node icons I use.

I don't add new features to Dynatree, since Fancytree is already released, sorry. But I think it would be possible to add node.data.iconTooltip to the icon span in a custom onRender callback.