@UiHandler("btnSuccessTxtArea")
 void onSuccessTxtArea(ClickEvent e) {
   txtArea.setSuccess("This is a success message text area.");
 }
 @UiHandler("btnClearTxtArea")
 void onClearTxtArea(ClickEvent e) {
   txtArea.clearErrorOrSuccess();
 }
 @UiHandler("btnErrorTxtArea")
 void onErrorTxtArea(ClickEvent e) {
   txtArea.setError("This is an error message for text area.");
 }