So, I have several "portable" Arduino IDE installations of various versions. Each one has the installed libraries located in its own "…\portable\sketchbook\libraries". That's fine as I can continue to compile my legacy projects using the libraries with which they were debugged.
But, I'd like to have a common directory containing libraries that I've written myself that could be accessed by all of the IDE installations. So, is there a way to add a custom folder to the library search path?