preferences:set in Framework Functions

• (preferences:set symbol value) -> void?
     symbol : symbol?
     value : any/c

  See also preferences:set-default.

  preferences:set-preference sets the preference symbol to value. This should be called when the users requests a change to a preference.

  This function immediately writes the preference value to disk.

  It raises exn:unknown-preference if the preference's default has not been set.