drscheme-ui.ss
;; drscheme-ui
;; Procedures which *may* be overridden by DrScheme to do useful things.
;; Or they may not be.

(module drscheme-ui mzscheme

  (provide has-backtrace?
           show-backtrace
           can-show-source?
           show-source
           initialized?
           
           ;; Only for use by DrScheme tool code.
           initialize)
  
  (define (has-backtrace? exn) #f)
  (define (show-backtrace exn) (void))
  (define can-show-source? #f)
  (define (show-source src pos span) (void))
  
  (define initialized? #f)
  (define (initialize -has-backtrace? -show-backtrace -show-source)
    (unless initialized?
      (set! has-backtrace? -has-backtrace?)
      (set! show-backtrace -show-backtrace)
      (set! can-show-source? #t)
      (set! show-source -show-source)
      (set! initialized? #t)))

  )