[plt-scheme] Reporting syntax-error to a DrScheme tool

Hi all,

I am attempting to hook up a css mode for DrScheme
and am missing the piece that makes DrScheme highlight
errors in the definition window.

In the parser I use

   ; css-parser : (-> token) -> sexp
   (define css-parser
     (parser
      (src-pos)
      ; TODO: wire the error function to the language level
      (error    (lambda (a name val start end)
                  (raise-read-error "read-error"
                                    (file-path)
                                    (position-line start)
                                    (position-col start)
                                    (position-offset start)
                                    (- (position-offset end)
                                       (position-offset start)))))
       ...

to raise an read-error.

In tool.ss I have the following on-execute method:

           (define/public (on-execute settings run-in-user-thread)
             ; (read-case-sensitive #f)
             (run-in-user-thread
              (lambda ()
                (error-display-handler
                 (drscheme:debug:make-debug-error-display-handler
                   (error-display-handler)))
                (void))))

When I click "Execute" on a file with syntax-error all I get is

   read-error

in the interaction window.

What piece of the puzzle is missing?

-- 
Jens Axel Søgaard