After clicking on a URL in Squeak I received a popup:

"There is no Web browser installed but the URL was copied to the clipboard:     http://lists.squeakfoundation.org/mailman/listinfo/beginners"

I am running on Linux MX and my default web browser is Waterfox.  All other URLs are OK  with that.  What can I do to inform Squeak that I do have a browser installed?