N°817 Portal: Linkset widget opening was throwing a warning message on IE9.

git-svn-id: http://svn.code.sf.net/p/itop/code/trunk@4886 a333f486-631f-4898-b8df-5754b55c2be0

sources/renderer/bootstrap/fieldrenderer/bslinkedsetfieldrenderer.class.inc.php

@@ -225,6 +225,7 @@ EOF
 						"displayLength": -1,
 						"scrollY": "300px",
 						"scrollCollapse": true,
+						"retrieve": true,
 						"order": [[iDefaultOrderColumnIndex, "asc"]],
 						"dom": 't',
 						"columns": getColumnsDefinition_{$this->oField->GetGlobalId()}(),