Close webform error messages
I found a neat little module the other day called Message Close which once installed, adds a simple close icon to every message, whether status or vaildation. It also resets all margins and padding so once a message is closed, the page looks exactly as it does on a fresh load.

In the js of the module, you can use jquery to make the message fade out, or slide out.

This would be perfect for closing webform validation messages without needing a page reload.