From b83e861f2e45c1ce52d228d0d8fd8874a55b797d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Georges=20Dup=C3=A9ron?= <georges.duperon@gmail.com>
Date: Sat, 29 Apr 2017 17:13:58 +0200
Subject: [PATCH] Pin the menu object while it is displayed, so that it is not
 garbage collected.

---
 gui-lib/mred/private/wx/gtk/menu.rkt | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/gui-lib/mred/private/wx/gtk/menu.rkt b/gui-lib/mred/private/wx/gtk/menu.rkt
index ffdea4fe..3ca2fab4 100644
--- a/gui-lib/mred/private/wx/gtk/menu.rkt
+++ b/gui-lib/mred/private/wx/gtk/menu.rkt
@@ -76,6 +76,10 @@
     (define/public (removing-item) (void))
     (super-new)))
 
+;; Globally reference any opened menu, so that the menu object stays alive
+;; while it is displayed, even if no other code refers to it.
+(define global-prevent-gc (make-hasheq))
+
 (defclass menu% widget%
   (init label
         callback
@@ -120,6 +124,8 @@
   (define cancel-none-box (box #t))
 
   (define/public (popup x y queue-cb)
+    ;; Pin the menu object so that it is not garbage collected while displayed
+    (hash-set! global-prevent-gc this #t)
     (set! on-popup queue-cb)
     (set! cancel-none-box (box #f))
     (gtk_menu_popup gtk 
@@ -148,6 +154,8 @@
   (define ignore-callback? #f)
 
   (define/public (do-selected menu-item)
+    ;; Allow the menu object to be garbage collected again
+    (hash-remove! global-prevent-gc this)
     ;; Called in event-pump thread
     (unless ignore-callback?
       (let ([top (get-top-parent)])
@@ -167,6 +175,8 @@
          [parent (send parent do-selected menu-item)]))))
 
   (define/public (do-no-selected)
+    ;; Allow the menu object to be garbage collected again
+    (hash-remove! global-prevent-gc this)
     ;; Queue a none-selected event, but only tentatively, because
     ;; the selection event may come later and cancel the none-selected
     ;; event.