public interface KeyboardEvents
Page.registerKey()  or at the widget level via
 Canvas.keyDown(), Canvas.keyPress(), and Canvas.keyUp().  Details about the key events can
 be retrieved via static methods on the EventHandler class including EventHandler.getKey(), EventHandler.getKeyEventCharacter()
 and EventHandler.getKeyEventCharacterValue(). 
 As with other Smart GWT event handling code,
 returning false will suppress the default native browser behavior.
 Note: browsers do not allow cancellation of some keys' default behaviors. These cases
 vary by browser, and wherever native cancellation is supported, returning false from your event
 handler should be sufficient to suppress the behavior. 
 Some specific cases where default
 behavior cancellation is not always possible include: 
f1, f3,
 f5, etc) which trigger native browser behavior.         [These can be suppressed in
 Internet Explorer and Mozilla Firefox but not in some other          browsers such as Safari /
 Chrome, etc]Alt+f3Windows / Apple key to show OS level menu)