var eventListeners = [];

function findEventListener(node, event, handler)
{
    var i;
    for (i in eventListeners)
    {
        if (eventListeners[i].node == node && eventListeners[i].event == event
         && eventListeners[i].handler == handler)
        {
            return i;
        }
    }
    return null;
}
function myAddEventListener(node, event, handler)
{
    if (findEventListener(node, event, handler) != null)
    {
        return;
    }

    if (!node.addEventListener)
    {
        node.attachEvent('on' + event, handler);
    }
    else
    {
        node.addEventListener(event, handler, false);
    }

    eventListeners.push({node: node, event: event, handler: handler});
}

function removeEventListenerIndex(index)
{
    var eventListener = eventListeners[index];
    delete eventListeners[index];
    
    if (!eventListener.node.removeEventListener)
    {
        eventListener.node.detachEvent('on' + eventListener.event,
                                       eventListener.handler);
    }
    else
    {
        eventListener.node.removeEventListener(eventListener.event,
                                               eventListener.handler, false);
    }
}

function myRemoveEventListener(node, event, handler)
{
    removeEventListenerIndex(findEventListener(node, event, handler));
}

function cleanupEventListeners()
{
    var i;
    for (i = eventListeners.length; i > 0; i--)
    {
        if (eventListeners[i] != undefined)
        {
            removeEventListenerIndex(i);
        }
    }
}