I'm using Vaadin and everything works fine, but there is one point I'm not happy about:
The notifications ( only show the message, but there is NOTHING which explains the user how to close it. Of course I can close it by clicking on it, but this is not intuitive in my opinion.
Notification.show("message part one", "message part two", Type.ERROR_MESSAGE);
You can display an X button.
See Valo Theme Demo, section notifications: use additional style "closable" (
Alternatively you could include text like "(click to close)" into your message.