diff --git a/collects/mred/private/wxcanvas.ss b/collects/mred/private/wxcanvas.ss
index 2bef5bab..5eb8efe4 100644
--- a/collects/mred/private/wxcanvas.ss
+++ b/collects/mred/private/wxcanvas.ss
@@ -224,5 +224,10 @@
                                                 0 0 #t #t)))
       (inherit editor-canvas-on-scroll)
       (define/override (on-scroll e)
-        (editor-canvas-on-scroll))
+        (if (or (eq? 'msw (system-type))
+                (eq? 'macosx (system-type)))
+            (queue-window-callback
+             this
+             (lambda () (editor-canvas-on-scroll)))
+            (editor-canvas-on-scroll)))
       (super-new))))
diff --git a/collects/mred/private/wxme/editor-canvas.ss b/collects/mred/private/wxme/editor-canvas.ss
index 1cf21f3b..7f76ceae 100644
--- a/collects/mred/private/wxme/editor-canvas.ss
+++ b/collects/mred/private/wxme/editor-canvas.ss
@@ -5,6 +5,7 @@
          "editor-admin.ss"
          "private.ss"
          (only-in "cycle.ss" popup-menu%)
+         (only-in "../helper.ss" queue-window-callback)
          "wx.ss")
 
 (provide editor-canvas%)
@@ -350,9 +351,17 @@
         (thunk)))
 
   (define/override (on-set-focus)
-    (on-focus #t))
+    (if (eq? 'msw (system-type))
+        (queue-window-callback
+         this
+         (lambda () (on-focus #t)))
+        (on-focus #t)))
   (define/override (on-kill-focus)
-    (on-focus #f))
+    (if (eq? 'msw (system-type))
+        (queue-window-callback
+         this
+         (lambda () (on-focus #f)))
+        (on-focus #f)))
 
   (define/public (is-focus-on?) focuson?)