Sorry for stupid question, is your plugin meant to appear in Draw menu? I placed it in plugins folder inside Sketchup package, but do not see it.

Thank you, Dave!
There was a small plus icon on the Entity Info panel, that was hiding length.

How to measure accurate arc length in Sketchup pro? Version 8.0.3161
Forum search doesn't return anything, though I am sure I am not the first one to ask.