change indentation strategy for sequences whose head is a keyword

assume that these are part of some internal structure of something
that, in general looks like

  (#:x 1 #:y 2 #:z 3)

and so prefer to indent like this:

  (#:x 1
   #:y 2
   #:z 3)

instead of like this:

  (#:x 1
       #:y 2
       #:z 3)

gui-lib/framework/private/racket.rkt

@@ -702,6 +702,8 @@
                     (- id-end contains)
                     0))
               (cond
+                [(first-sexp-is-keyword? contains)
+                 (visual-offset contains)]
                 [(second-sexp-is-ellipsis? contains)
                  (visual-offset contains)]
                 [(not (find-up-sexp pos))
@@ -739,6 +741,13 @@
                                       (not (= (position-paragraph thrd-start)
                                               (position-paragraph snd-start)))))))))))))
 
+    (define/private (first-sexp-is-keyword? contains)
+      (let ([fst-end (get-forward-sexp contains)])
+        (and fst-end
+             (let ([fst-start (get-backward-sexp fst-end)])
+               (and fst-start
+                    (equal? (classify-position fst-start) 'hash-colon-keyword))))))
+    
     (define/public (tabify-selection [start-pos (get-start-position)]
                                      [end-pos (get-end-position)])
       (unless (is-stopped?) 

gui-test/framework/tests/racket.rkt

@@ -171,6 +171,10 @@
                   "(r a\n   b\n   c\n   d\n   e\n   f\n   g")
 (test-indentation "(r a b\nc d\ne f\ng h"
                   "(r a b\n   c d\n   e f\n   g h")
+(test-indentation "(#:x\n1)"
+                  "(#:x\n 1)")
+(test-indentation "(#:x 0\n1)"
+                  "(#:x 0\n 1)")
 
 
 (define (test-magic-square-bracket which before after)