diff --git a/collects/framework/frame.ss b/collects/framework/frame.ss
index 65daf238..21245738 100644
--- a/collects/framework/frame.ss
+++ b/collects/framework/frame.ss
@@ -71,10 +71,12 @@
       (override
 	[can-close?
 	 (lambda ()
-	   (and (super-can-close?)
-		(send (group:get-the-frame-group)
-		      can-remove-frame?
-		      this)))]
+           (let ([super (super-can-close?)]
+                 [group
+                  (send (group:get-the-frame-group)
+                        can-remove-frame?
+                        this)])
+             (and super group)))]
 	[on-close
 	 (lambda ()
 	   (super-on-close)
@@ -85,7 +87,11 @@
 	 (lambda (on?)
 	   (super-on-focus on?)
 	   (when on?
-	     (send (group:get-the-frame-group) set-active-frame this)))])
+	     (send (group:get-the-frame-group) set-active-frame this)))]
+        
+        [on-drop-file
+         (lambda (filename)
+           (handler:edit-file filename))])
 
       (inherit show)
       (public
@@ -100,6 +106,7 @@
 	     (on-close)
 	     (show #f)))])
       
+      (inherit accept-drop-files)
       (sequence
 	(let ([mdi-parent (send (group:get-the-frame-group) get-mdi-parent)])
 	  (super-init label
@@ -110,6 +117,8 @@
 		       [mdi-parent (cons 'mdi-child style)]
 		       [else style])))
 
+        (accept-drop-files #t)
+
 	(make-object menu% "Windows" (make-object (get-menu-bar%) this))
 	(reorder-menus this)
 	(send (group:get-the-frame-group) insert-frame this))
diff --git a/collects/framework/group.ss b/collects/framework/group.ss
index a385df60..44ec055e 100644
--- a/collects/framework/group.ss
+++ b/collects/framework/group.ss
@@ -157,7 +157,7 @@
 		   f frames
 		   (lambda (f fr) (eq? f (frame-frame fr))))])
 	     (if (null? new-frames)
-		 (empty-test)
+                 (empty-test)
 		 #t)))]
 	[remove-frame
 	 (opt-lambda (f)
diff --git a/collects/framework/scheme.ss b/collects/framework/scheme.ss
index 9b4677af..aabf02f1 100644
--- a/collects/framework/scheme.ss
+++ b/collects/framework/scheme.ss
@@ -395,8 +395,7 @@
 		  [visual-offset
 		   (lambda (pos)
 		     (let loop ([p (sub1 pos)])
-		       (if (= p -1)
-			   0
+		       (if p
 			   (let ([c (get-character p)])
 			     (cond
 			      [(char=? c #\null) 0]
@@ -404,7 +403,8 @@
 			       (let ([o (loop (sub1 p))])
 				 (+ o (- 8 (modulo o 8))))]
 			      [(char=? c #\newline) 0]
-			      [else (add1 (loop (sub1 p)))])))))]
+			      [else (add1 (loop (sub1 p)))]))
+			   0)))]
 		  [do-indent
 		   (lambda (amt)
 		     (let* ([pos-start end]
@@ -645,11 +645,17 @@
 			   exp-pos))])
 
 	     (if (and exp-pos (> exp-pos 0))
-		 (let ([pos (apply max
-				   (map paren-pos (scheme-paren:get-paren-pairs)))])
-		   (if (= pos -1)  ;; all finds failed
+		 (let ([poss (let loop ([parens (scheme-paren:get-paren-pairs)])
+                              (cond
+                                [(null? parens) null]
+                                [else 
+                                 (let ([pos (paren-pos (car parens))])
+                                   (if pos
+                                       (cons pos (loop (cdr parens)))
+                                       (loop (cdr parens))))]))])
+		   (if (null? poss) ;; all finds failed
 		       #f
-		       (- pos 1))) ;; subtract one to move outside the paren
+                       (- (apply max poss) 1))) ;; subtract one to move outside the paren
 		 #f)))]
 	[up-sexp
 	 (lambda (start-pos)