private void initParamsEditor(final InitialPageData pageData) { ParamsEditorApp.onModuleLoad(pageData); paramsEditor = ParamsEditorApp.getPanel(); paramsEditor .getValidationController() .addValueChangeHandler( new ValueChangeHandler<ClientValue>() { @Override public void onValueChange(final ValueChangeEvent<ClientValue> event) { runButton.setEnabled(paramsEditor.isValid()); updateTitleFromFileTable(); updateOutputLocation(); } }); }