controlNamesItem.setWidth(300);
controlNamesItem.addChangedHandler(new ChangedHandler() {
public void onChanged(ChangedEvent event) {
// determine the control that was selected and remember information about it
selectedControlName = (String) event.getValue();
ServerPluginControlDefinition def = getControlDefinition(selectedControlName);
selectedParamsDef = def.getParameters();
selectedResultsDef = def.getResults();
// we changed the control selected, hide any previously shown results
resultsLayout.destroyMembers();
resultsLayout.setVisible(false);