made drs remember the frame's position and use it for the initial position

svn: r6676

collects/drscheme/private/main.ss

@@ -57,6 +57,12 @@
                                      (finder:default-filters)))
       (application:current-app-name (string-constant drscheme))
 
+  (preferences:set-default 'drscheme:frame:initial-position #f 
+                           (λ (x) (or (not x)
+                                      (and (pair? x)
+                                           (number? (car x))
+                                           (number? (cdr x))))))
+  
   (preferences:set-default 'drscheme:limit-memory #f
                            (λ (x) (or (boolean? x)
                                       (integer? x)

collects/drscheme/private/unit.ss

@@ -1157,6 +1157,9 @@ module browser threading seems wrong.
                    file-menu:get-revert-item
                    file-menu:get-print-item)
           
+          (define/override (on-move x y)
+            (preferences:set 'drscheme:frame:initial-position (cons x y)))
+
           ;; logging : (union #f string[directory-name])
           (field [logging #f]
                  [definitions-log-counter 0]  ;; number
@@ -3607,9 +3610,15 @@ module browser threading seems wrong.
             [else
              (create-new-drscheme-frame name)])]))
     
+    (define first-frame? #t)
       (define (create-new-drscheme-frame filename)
         (let* ([drs-frame% (drscheme:get/extend:get-unit-frame)]
                [frame (new drs-frame% (filename filename))])
           (send (send frame get-interactions-text) initialize-console)
+          (when first-frame?
+            (let ([pos (preferences:get 'drscheme:frame:initial-position)])
+              (when pos
+                (send frame move (car pos) (cdr pos)))))
+          (set! first-frame? #f)
           (send frame show #t)
           frame))))