racket/gui: fix problem with reparent and container sequences

In a container sequence, hides and shows are delayed, but
reparenting needs the hide operation to really complete.

pkgs/gui-pkgs/gui-lib/mred/private/mrcontainer.rkt

@@ -40,7 +40,8 @@
 
 (define-local-member-name
   has-wx-child?
-  adopt-wx-child)
+  adopt-wx-child
+  forget-wx-child)
 
 (define (make-container% %) ; % implements area<%>
   (class* % (area-container<%> internal-container<%>)
@@ -156,14 +157,14 @@
              is-shown?
              show)
     (define/public (reparent new-parent)
-      (check-container-parent '(subwindow<%> reparent) new-parent)
+      (check-container-parent '(method subwindow<%> reparent) new-parent)
       (unless (as-entry
                (lambda ()
                  (let ([p1 (send (mred->wx this) get-top-level)]
                        [p2 (send (mred->wx new-parent) get-top-level)])
                    (eq? (send p1 get-eventspace) (send p1 get-eventspace)))))
         (raise-arguments-error
-         (who->name '(subwindow<%> reparent))
+         (who->name '(method subwindow<%> reparent))
          "current parent's eventspace is not the same as the eventspace of the new parent"
          "subwindow" this
          "new parent" new-parent))
@@ -171,7 +172,7 @@
         (when p
           (when (eq? p this)
             (raise-arguments-error
-             (who->name '(subwindow<%> reparent))
+             (who->name '(method subwindow<%> reparent))
              (if (eq? new-parent this)
                  "cannot set parent to self"
                  "cannot set parent to a descedant")
@@ -192,6 +193,7 @@
                               (or (eq? p wx)
                                   (loop (send p get-parent)))))
                  ;; Ok --- really reparent:
+                 (send wx ensure-forgotten)
                  (send new-parent adopt-wx-child wx)
                  (set-parent new-parent))))))
         (when added?

pkgs/gui-pkgs/gui-lib/mred/private/wxpanel.rkt

@@ -144,8 +144,15 @@
                                     (set! hidden-child (car children))
                                     (let ([i (send hidden-child get-info)])
                                       (set-min-width (child-info-x-min i))
-                                      (set-min-height (child-info-y-min i))))]
+                                      (set-min-height (child-info-y-min i))))])
+      
+      (override*
+       [ensure-forgotten (lambda ()
+                           (for ([c (in-list children)])
+                             (send c ensure-forgotten))
+                           (super ensure-forgotten))])
 
+      (public*         
        [border
         (case-lambda
           [() curr-border]

pkgs/gui-pkgs/gui-lib/mred/private/wxtop.rkt

@@ -226,6 +226,12 @@
           (when (zero? seq-count)
             (delay-updates #f)))]
 
+       [forget-child
+        (lambda (child)
+          (unless (hash-ref show-ht child #t)
+            (send child show #f))
+          (hash-remove! show-ht child))]
+
        [show-child
         (lambda (child show?)
           (if perform-updates?

pkgs/gui-pkgs/gui-lib/mred/private/wxwindow.rkt

@@ -92,7 +92,12 @@
                       (is-a? window wx:dialog%)) 
                   (set! top-level window)]
                  [else (loop (send window get-parent))])))
-            top-level)])
+            top-level)]
+         [ensure-forgotten
+          (lambda ()
+            ;; This value or its ancestor is going to be adopted elsewhere,
+            ;; so really forget it, make sure it's hidden, etc.
+            (send (get-top-level) forget-child this))])
         (public*
          [really-show
           (lambda (on?)