> Please excuse me if you people think I am pushing it too hard (it's just my first attempt at development at bokeh, and I am not fully aware of its ideology)!

Not problem, we encouraged people to submit PRs! But we also do extensive reviews even in little PRs like you are proposing, because it is good for us (the project) and it is good for you because you quickly can get feedback and notices about some of the Bokeh internals.

Coming to the PR implementation, I think you can do a little change in you code to output the repeated tools identity in the warning...

@bryevdv, do you want to add something else?