Complete wxEVT_MENU_{OPEN,CLOSE} implementation in wxMSW and wxOSX.

Set the wxMenu correctly for wxEVT_MENU_CLOSE events in wxMSW.

Set the menu id correctly to allow wxMenuEvent::IsPopup() to work for both
wxEVT_MENU_OPEN and wxEVT_MENU_CLOSE in wxOSX.

Closes #11313.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@70151 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/event.h

@@ -3870,9 +3870,12 @@ public:
     wxMenuEvent(wxEventType type = wxEVT_NULL, int id = 0, wxMenu* menu = NULL);
 
     /**
-        Returns the menu which is being opened or closed. This method should only be
-        used with the @c OPEN and @c CLOSE events and even for them the
-        returned pointer may be @NULL in some ports.
+        Returns the menu which is being opened or closed.
+
+        This method can only be used with the @c OPEN and @c CLOSE events.
+
+        The returned value is never @NULL in the ports implementing this
+        function, which currently includes all the major ones.
     */
     wxMenu* GetMenu() const;