added menubar update OnActivate for multiple frames with their own menubars, it's not perfect (menu merge) would be better, but at last something

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@9441 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/mac/menu.cpp

@@ -631,6 +631,9 @@ void wxMenuBar::RebuildAccelTable()
 
 void wxMenuBar::MacInstallMenuBar() 
 {
+	if ( s_macInstalledMenuBar == this )
+		return ;
+		
   	Handle menubar = ::GetNewMBar( kwxMacMenuBarResource ) ;
   	wxString message ;
   	wxCHECK_RET( menubar != NULL, "can't read MBAR resource" );