public Object execute(ExecutionEvent event) throws ExecutionException {
IWorkbenchWindow window = HandlerUtil.getActiveWorkbenchWindow(event);
IWorkbenchPage page = window.getActivePage();
try {
page.openEditor(new MetadataRuleEditorInput(), MetadataRuleEditor.ID);
} catch (PartInitException e) {
e.printStackTrace();
}
return null;
}