Cocoa: avoid over-eager refresh on OS X 10.11

A relatively late correction to refresh handling for El Capitan
(commit 9bf18505d5) causes a canvas to be refreshed too often
in some cases. Delay the refresh to restore the old timing
without the old bug.

gui-lib/mred/private/wx/cocoa/frame.rkt

@@ -430,7 +430,10 @@
         (tellv cocoa enableFlushWindow)
         (when (version-10.11-or-later?)
           (tellv cocoa setAutodisplay: #:type _BOOL #t)
-          (tellv cocoa displayIfNeeded))))
+          (queue-window-refresh-event
+           this
+           (lambda ()
+             (tellv cocoa displayIfNeeded))))))
 
     (define/public (force-window-focus)
       (let ([next (get-app-front-window)])

gui-lib/mred/private/wxme/editor-canvas.rkt

@@ -306,14 +306,14 @@
            (maybe-reset-size))))))
 
   (define/private (maybe-reset-size)
-    (begin-refresh-sequence)
     (let-boxes ([w 0]
                 [h 0])
         (get-size w h)
       (unless (and (= w lastwidth)
                    (= h lastheight))
-        (reset-size)))
-    (end-refresh-sequence))
+        (begin-refresh-sequence)
+        (reset-size)
+        (end-refresh-sequence))))
 
   (define/private (reset-size)
     (reset-visual #f)