This class represents DOM Events.
Not all user actions have obvious trigger - you need sometimes to study the DOM to find out, what DOM Event needs to be triggered to fire the action (it mostly hides in event attributes, such as onmouseover, onclick, etc.). For this purpose you can use Firebug.
You can fire the event using fireEvent method on the specific element.
You can select one from events listed in Event class, or you can specify your own by extending this class (it should not be necessary since the list is close to complete).