fixed searching bugs

new preferences
fixed load bugs

original commit: d44b20eb9934fe09d3a652f35401bf4c3d22cf0e

collects/mred/edit.ss

@@ -15,12 +15,18 @@
 	    
     (mred:debug:printf 'invoke "mred:edit@")
 
-    (mred:preferences:set-preference-default 'mred:verify-change-format #f)
+    (mred:preferences:set-preference-default 'mred:verify-change-format #f 
+					     (lambda (x)
+					       (or (not x)
+						   (eq? x #t))))
 
     (define-struct range (start end b/w-bitmap color))
     (define-struct rectangle (left top width height b/w-bitmap color))
 
-    (mred:preferences:set-preference-default 'mred:auto-set-wrap? #f)
+    (mred:preferences:set-preference-default 'mred:auto-set-wrap? #f
+					     (lambda (x)
+					       (or (not x)
+						   (eq? x #t))))
 
     (define make-snip%
       (let ([sl (make-object wx:style-list%)])

collects/mred/finder.ss

@@ -40,7 +40,10 @@
 	  #t]
 	 [else #f])))
 
-    (mred:preferences:set-preference-default 'mred:show-periods-in-dirlist #f)
+    (mred:preferences:set-preference-default 'mred:show-periods-in-dirlist #f
+					     (lambda (x)
+					       (or (not x)
+						   (eq? x #t))))
 
     (define finder-dialog%
       (class mred:container:dialog-box% (save-mode? replace-ok? multi-mode? 
@@ -538,7 +541,11 @@
     (mred:preferences:set-preference-default 'mred:file-dialogs
 					     (if (eq? wx:platform 'unix)
 						 'common
-						 'std))
+						 'std)
+					     (lambda (x)
+					       (or (eq? x 'common)
+						   (eq? x 'std))))
+
     (define put-file
       (lambda args
 	(apply (case (mred:preferences:get-preference 'mred:file-dialogs)

collects/mred/keys.ss

@@ -44,7 +44,11 @@
 		    (send keymap map-function key func))
 		  (make-meta-prefix-list key))))
 
-    (mred:preferences:set-preference-default 'mred:delete-forward? (not (eq? wx:platform 'unix)))
+    (mred:preferences:set-preference-default 'mred:delete-forward? 
+					     (not (eq? wx:platform 'unix))
+					     (lambda (x)
+					       (or (not x)
+						   (eq? x #t))))
 
     ; This installs the standard keyboard mapping
     (define setup-global-keymap
@@ -52,7 +56,10 @@
       (let* ([rcs
 	      (let ([last-checkin-string ""])
 		(mred:preferences:set-preference-default 
-		 'rcs-pathname (list "/usr/local/RCS/" "/usr/bin/" "/usr/local/bin/"))
+		 'rcs-pathname (list "/usr/local/RCS/" "/usr/bin/" "/usr/local/bin/")
+		 (lambda (x)
+		   (and (list? x)
+			(andmap string? x))))
 		(lambda (edit event)
 		  (let/ec k
 		    (let* ([rcs-binaries (list "ci" "co" "rlog")]

collects/mred/prefs.ss

@@ -24,6 +24,7 @@
     (define-struct un/marshall (marshall unmarshall))
     (define-struct marshalled (data))
     (define-struct pref (value))
+    (define-struct default (value checker))
 
     (define guard
       (lambda (when p value thunk)
@@ -83,14 +84,22 @@
 					     ((debug-info-handler))))))])
 	  (cond
 	    [(marshalled? ans)
-	     (let* ([unmarshalled (unmarshall p ans)]
-		    [default
+	     (let* ([default-s
 		      (hash-table-get
 		       defaults p
 		       (lambda ()
 			 (error 'get-preference
 				"no default pref for: ~a~n"
 				p)))]
+		    [default (default-value default-s)]
+		    [checker (default-checker default-s)]
+		    [unmarshalled (let ([unmarsh (unmarshall p ans)])
+				    (if (checker unmarsh)
+					unmarsh
+					(begin
+					  (printf "WARNING: ~s rejecting invalid pref ~s in favor of ~s~n"
+						  p unmarsh default)
+					  default)))]
 		    [_ (mred:debug:printf 'prefs "get-preference checking callbacks: ~a to ~a"
 					  p unmarshalled)]
 		    [pref (if (check-callbacks p unmarshalled)
@@ -140,16 +149,19 @@
 	(mred:debug:printf 'prefs "finished setting prefs to default values")))
     
     (define set-preference-default
-      (lambda (p value)
+      (lambda (p value checker)
 	(mred:debug:printf 'prefs "setting default value for ~a to ~a" p value)
 	(hash-table-get preferences p 
 			(lambda () 
 			  (hash-table-put! preferences p (make-pref value))))
-	(hash-table-put! defaults p value)))
+	(hash-table-put! defaults p (make-default value checker))))
     
     ;; this is here becuase exit has to come before
     ;; prefs.ss in the loading order.
-    (set-preference-default 'mred:verify-exit #t)
+    (set-preference-default 'mred:verify-exit #t
+			    (lambda (x)
+			      (or (not x)
+				  (eq? x #t))))
 
     (define save-user-preferences 
       (let ([marshall-pref