In certain modal dialogues, we listen on the Escape key to close a
dialogue. However, this is still passed to the browser. As a result, if the
browser is in full screen mode and that browser respects the escape key as
a means to exit full screen.
As a result, we need to ensure that we listen for the escape key at keydown
rather than keyup, and additionally prevent the default browser behaviour.
This is a workaround to http://yuilibrary.com/projects/yui3/ticket/2532616
and, should that issue be fixed, it should be removed.
Andrew Robert Nicols
d2e360710f