It would be nice to be able to copy the path to the preferences file so it's easier to remember /
access after quitting.

probably better to just have it open the parent directory when you click
it... for most platforms, being able to select the path doesn't do much for
you--if it's on the clipboard, what do you do with the path?

i had code in there to open the file when you clicked it, but as soon as
you quit (to make changes), things are overwritten. i hadn't implemented
the open parent folder out of concern for the same issue--that people would
make changes to the file while processing was still running. i supposed it
could also check for whether the file had been updated outside of p5, and
show a warning to the user that their changes will be lost... but that's
um, getting complicated.

k, i've made it highlight as a link on mouse over, and clicking it opens
the parent folder. by opening the parent folder we avoid people trying to
edit the file while the PDE is still running.