Description:
This patch makes events sink lazily on common GWT widgets. This is a  breaking change, as any subclasses which depend upon the events being sunk without adding listeners will no longer work.

Issue: 1491.
Review by: knorton


git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@1780 8db76d5a-ed1c-0410-87a9-c151d255dfc7