diff --git a/collects/mred/private/wx/cocoa/window.rkt b/collects/mred/private/wx/cocoa/window.rkt
index 5a470bf682..06a6491f8e 100644
--- a/collects/mred/private/wx/cocoa/window.rkt
+++ b/collects/mred/private/wx/cocoa/window.rkt
@@ -49,6 +49,19 @@
       (unless (do-mouse-event wx event 'motion #t #f #f)
         (super-tell #:type _void mouseDragged: event))]
   [-a _void (mouseMoved: [_id event]) 
+      ;; This event is sent to the first responder, instead of the
+      ;; view under the mouse.
+      (let* ([win (tell event window)]
+             [view (and win (tell win contentView))]
+             [hit (and view (tell view hitTest: #:type _NSPoint 
+                                  (tell #:type _NSPoint event locationInWindow)))])
+        (let loop ([hit hit])
+          (when hit
+            (if (tell #:type _BOOL hit respondsToSelector: #:type _SEL (selector doMouseMoved:))
+                (tell hit doMouseMoved: event)
+                (loop (tell hit superview))))))]
+  [-a _void (doMouseMoved: [_id event]) 
+      ;; called by mouseMoved:
       (unless (do-mouse-event wx event 'motion #f #f #f)
         (super-tell #:type _void mouseMoved: event))]
   [-a _void (mouseEntered: [_id event]) 
diff --git a/collects/mred/private/wx/common/freeze.rkt b/collects/mred/private/wx/common/freeze.rkt
index d5dc26d02d..11a8278d1e 100644
--- a/collects/mred/private/wx/common/freeze.rkt
+++ b/collects/mred/private/wx/common/freeze.rkt
@@ -36,6 +36,30 @@
               freeze-tag)))))
       (void))))
 
+(define (internal-error str)
+  (log-error
+   (apply string-append
+          (format "internal error: ~s" str)
+          (for/list ([c (continuation-mark-set->context (current-continuation-marks))])
+            (let ([name (car c)]
+                  [loc (cdr c)])
+              (cond
+               [loc
+                (string-append
+                 "\n"
+                 (cond 
+                  [(srcloc-line loc)
+                   (format "~a:~a:~a" 
+                           (srcloc-source loc)
+                           (srcloc-line loc)
+                           (srcloc-column loc))]
+                  [else
+                   (format "~a::~a" 
+                           (srcloc-source loc)
+                           (srcloc-position loc))])
+                 (if name (format " ~a" name) ""))]
+               [else (format "\n ~a" name)]))))))
+
 ;; FIXME: waiting 200msec is not a good enough rule.
 (define (constrained-reply es thunk default [should-give-up?
                                              (let ([now (current-inexact-milliseconds)])
@@ -43,7 +67,7 @@
                                                  ((current-inexact-milliseconds) . > . (+ now 200))))])
   (let ([b (freezer-box)])
     (unless b
-      (log-error "internal error: constrained-reply not within an unfreeze point"))
+      (internal-error "constrained-reply not within an unfreeze point"))
     (if (eq? (current-thread) (eventspace-handler-thread es))
         (if (pair? b)
             ;; already suspended, so push this work completely:
@@ -79,5 +103,5 @@
                            (scheme_restore_on_atomic_timeout prev))))
                    freeze-tag))))))
         (begin
-          (log-error "internal error: wrong eventspace for constrained event handling\n")
+          (internal-error "wrong eventspace for constrained event handling\n")
           default))))