mred:set-preference-default

• (mred:set-preference-default symbol value test) -> void
      symbol : symbol
      value : any scheme value
      test : a function that takes any scheme value and returns a boolean

  This sets the default value of the preference symbol to value. If the user has chosen a different setting, the users setting will take precedence over the default value.

  The last argument, test is used as a safeguard. That function is called to determine if a preference read in from a file is avlid preference. If test returns #t, then the preference is treated as valid. If test returns #f then the default is used.