// Custom events to allow multiple things to happen when a date input is changed
// It'd be nice to use the standard DOM interfaces to do this, but IE6 doesn't support them.
// They could be monkeypatched in if it supported Node.prototype... but it doesn't.
// (Adding a behaviour is too cumbersome.)

// Modeled after Prototype's Event.

var CustomEvent = {
	observe: function (target, type, listener) {
		target = $(target);
		
		if (!('customEventListeners' in target)) {
			target.customEventListeners = {};
		}
		
		// create an array to hold the listeners for an event, if it doesn't already exist
		if (!(type in target.customEventListeners)) {
			target.customEventListeners[type] = [];
		}
		
		// add the new listener only if it's not already there
		if (!(target.customEventListeners[type].include(listener))) {
			target.customEventListeners[type].push(listener);
		}
	},
	
	dispatch: function (target, evt) {
		target = $(target);
		
		// no listeners? do nothing and return
		if (!('customEventListeners' in target)) return;
		if (!(evt.type in target.customEventListeners)) return;
		
		// call each listener with the event
		evt.target = target;
		target.customEventListeners[evt.type].each(function (listener) {
			listener(evt);
		});
	},
	
	stopObserving: function (target, type, listener) {
		target = $(target);
		
		if (!('customEventListeners' in target)) return;
		
		// shorter name
		var listeners = target.customEventListeners;
		
		if (!(type in listeners)) return;
		
		listeners[type].each(function (current_listener, i) {
			if (current_listener == listener) {
				delete listeners[type][i];
				return;
			}
		});
	}
}