ISelection selection = event.getSelection();
if (!selection.isEmpty() && selection instanceof TreeSelection) {
TreeSelection s = (TreeSelection) selection;
Object firstElement = s.getFirstElement();
if (firstElement instanceof RuleApplyNode) {
RuleApplyNode node = (RuleApplyNode) firstElement;
FeatureStructure fs = node.getFeatureStructure();
if (fs.getType().getName().equals(ExplainConstants.RULE_APPLY_TYPE)) {
Type t = fs.getType();
Feature featureId = t.getFeatureByBaseName(ExplainConstants.ID);
Feature featureScript = t.getFeatureByBaseName(ExplainConstants.SCRIPT);
int id = fs.getIntValue(featureId);