SelectionListener evaluationTrigger = new EvaluationTrigger(query, namespacesTable, prettyPrint, result);
query.addSelectionListener(evaluationTrigger);
execute.addSelectionListener(evaluationTrigger);
// add namespace loader listener
SelectionListener namespaceLoaderListener = new NamespaceLoadTrigger(query, namespacesTable);
namespaceLoader.addSelectionListener(namespaceLoaderListener);
}