A small thing: I discovered today that the name of metro's help file in doc/5.reference is 'metro.pd 'rather than 'metro-help.pd'. Every other help patch I've seen has the '-help' ending to it. On my old MacBook with vanilla 42.5, there is no problem right-clicking and asking for the patch, but I was helping a friend whose just learning Pd and has a newer MacBook and the latest release of vanilla for Mac, and it wouldn't load the help patch until I renamed the file 'metro-help.pd'.
Obviously this is a very small detail, but it just so happened to derail our work for about 1/2 an hour until I found the root of the problem. So heads up. Also, I'm curious as to why metro's helpfile isn't titled metro-help.pd and why it loads on some versions of pd, but not others.
-David