Make it possible to subclass wxMenuBar in XRC (patch #11679).

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63467 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/xrc/xh_menu.cpp

@@ -148,7 +148,17 @@ wxMenuBarXmlHandler::wxMenuBarXmlHandler() : wxXmlResourceHandler()
 
 wxObject *wxMenuBarXmlHandler::DoCreateResource()
 {
-    wxMenuBar *menubar = new wxMenuBar(GetStyle());
+    wxMenuBar *menubar = NULL;
+
+    const int style = GetStyle();
+    wxASSERT_MSG(!style || !m_instance,
+                 "cannot use <style> with pre-created menubar");
+
+    if ( m_instance )
+        menubar = wxDynamicCast(m_instance, wxMenuBar);
+    if ( !menubar )
+        menubar = new wxMenuBar(style);
+
     CreateChildren(menubar);
 
     if (m_parentAsWindow)