subscribe
fun <E : Event, T : EventTarget> T.subscribe(eventName: String, capture: Boolean = false, selector: E.() -> Boolean = { true }): Listener<E, T>
Creates a Listener for the given Event type and eventName.
Return
a Listener-object, which is more or less a Flow of the specific Event-type.
Parameters
eventName 
the DOM-API name of an event. Can be a custom name.
capture
if true, activates capturing mode, else remains in bubble mode (default)
selector
optional lambda expression to select specific events with option to manipulate it (e.g. preventDefault or stopPropagation).