adjusted how paren matching inside {} works for better tabbing in scribble mode

collects/framework/private/scheme.rkt

@@ -580,6 +580,12 @@
                   (let* ([proc-name (get-proc)])
                     (or (eq? proc-name 'define)
                         (eq? proc-name 'lambda))))]
+               [curley-brace-sexp?
+                (λ ()
+                  (define up-p (find-up-sexp pos))
+                  (and up-p
+                       (equal? #\{ (get-character up-p))))]
+               
                [indent-first-arg (λ (start) (car (find-offset start)))])
             (when (and is-tabbable?
                        (not (char=? (get-character (sub1 end))
@@ -598,15 +604,31 @@
               [(not contains)
                ;; Something went wrong matching. Should we get here?
                (do-indent 0)]
+              [(curley-brace-sexp?)
+               ;; when we are directly inside an sexp that uses {}s,
+               ;; we indent in a more C-like fashion (to help Scribble)
+               (define first-curley (find-up-sexp pos))
+               (define containing-curleys
+                 (let loop ([pos first-curley])
+                   (let ([next (find-up-sexp pos)])
+                     (if (and next
+                              (equal? (get-character next) #\{))
+                       (+ (loop next) 1)
+                       1))))
+               (define close-first-curley (get-forward-sexp first-curley))
+               (define para (position-paragraph pos))
+               (when (<= (paragraph-start-position para) close-first-curley (paragraph-end-position para))
+                 (set! containing-curleys (max 0 (- containing-curleys 1))))
+               (do-indent (* containing-curleys 2))]
               [(not last) 
                ;; We can't find a match backward from pos,
                ;;  but we seem to be inside an S-exp, so 
                ;;  go "up" an S-exp, and move forward past
                ;;  the associated paren
                (let ([enclosing (find-up-sexp pos)])
-                 (do-indent (if enclosing
+                 (if enclosing
-                                (+ (visual-offset enclosing) 1)
+                   (do-indent (+ (visual-offset enclosing) 1))
-                                0)))]
+                   (do-indent 0)))]
               [(= contains last)
                ;; There's only one S-expr in the S-expr
                ;;  containing "pos"