Provides methods used for event handling. It is typically mixed in by concrete classes
such as OM.Map or OM.Layer which generates events.  It's not meant to be used directly.
Methods
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    <static> on()
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    A shorthand name for the member function addListener. 
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    addListener(eventType, f, context)
- 
    
    Attaches an event listener for the given event type under the given 
 context.Parameters:Name Type Description eventTypeString The event type, which is typically specific to the class 
 that mixes in EventSource.ffunction The listener function contextObject An optional context; The default is this. 
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    deleteAllListeners()
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    removes all listeners currently registered on this instance, regardless 
 of their type.
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    deleteListener(eventType, f, context)
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    Removes the given listener function previously registered. Parameters:Name Type Description eventTypeString type of listener event ffunction the listener function contextObject An optional context 
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    deleteListeners()
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    Removes all listeners of the specified type from this instance. 
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    getListeners(eventType)
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    Returns an array of listeners for the specified event type. Parameters:Name Type Description eventTypeString The event type 
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    hasListener(eventType, handler, ctx)
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    Checks if any listeners have been registered for the given type. Parameters:Name Type Description eventTypeString The event type to check for listeners handlerObject The event type handler. Optional ctxObject The handler context. Optional Returns:True if listener exists, false otherwise. - Type
- Boolean