added 'centered' property to wxDialog handler

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@8110 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

contrib/src/xml/xh_dlg.cpp

@@ -62,6 +62,9 @@ wxObject *wxDialogXmlHandler::DoCreateResource()
 
     CreateChildren(dlg);
     
+    if (GetBool(_("centered"), FALSE))
+        dlg->Centre();
+    
     return dlg;
 }