The conflict I see is that the same state (a selected node) has different behaviour based on how it got selected, which breaks the model.
I could see a case to not update in realtime whilst selecting, and of course there's no support for multiple selections.
Here's my thinking: on mouseUp, if one node is selected, show the node documentation for it.
For an application I am working on, it would be useful to do the same thing that the Vuo.app does as a result of Tools>Canvas Transparency. Ie, I would like to change the opacity of the window, or better, to set a transparent background.