Use event modifiers and accessors rather than m_ variables directly, which are now protected rather than public with 2.4 compatibility disabled

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@31454 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/os2/listbox.cpp

@@ -810,7 +810,7 @@ bool wxListBox::OS2Command(
     {
         n = -1;
     }
-    vEvent.m_commandInt = n;
+    vEvent.SetInt(n);
     return GetEventHandler()->ProcessEvent(vEvent);
 } // end of wxListBox::OS2Command