or are quite big like this one that will become part of my ongoing project of a geologic earth:
So I would extend your outline of an information pane by possibilities of free positioning and free size definition and, additionally, by a page switching mechanism for those legends that are even too big to be presented completely on the screen. Thus an addon could be packaged with all necessary and additional informations that now are only present in the readme files and *.scc comments. Not only technical textures would benefit from that. Conceptual addons like black holes, pulsars and others could explain their purpose, limits and asumptions made. And designers of custom systems could explain their fantasy worlds in details or point out certain highlights.
But I still wouldn't leave the ideas of floating overlay information or information on custom bodies. They have their own purposes. Informational custom bodies could be of good use with (educational) scripts. Besides their implementation is possible without depending on a certain celestia version, they are also good stopping points. And giving them a funny shape could be of good use especially for children following the lesson.
I think all this is worth of further/deeper considerations.
have nice days,
maxim.
