#5 User editable node annotations

[Brendan Cleary]

We want to implement a use case where by the user can
attach a string annotation to a node and have control
over the display of that annotation. This is probably
most easily implemented by duplicating the current node
text capability used to display the node name with
another scene graph node onto which the annotation can
be rendered. We also need to provide an interface that
accepts a node and the annotation as a string, which
when invoked by a client application identifies the
node in the graph and updates the text annotation of
that node to the given string.