function addEvent(element , type , fun){
    if (!element.events) element.events = {};
    var handlers = element.events[type];
    if (!handlers) {
        handlers = element.events[type] = [];
        if(element['on' + type]) {      
            handlers[0] = element['on' + type];
        }
    }
    handlers.append( fun , true)   
    element['on' + type] = handleEvent;
}
function removeEvent(element , type , fun) {
    if (element.events && element.events[type]) {
        element.events[type].remove(fun);
    }
}
function handleEvent(event) {
    var returnValue = true , i=0;
    event = event || fixEvent(window.event);
    var handlers = this.events[event.type] , length = handlers.length;
    for ( ;i < length ;i++) {
        if ( handlers[i].call( this , event) === false ){
            returnValue = false;
        }
    }
    return returnValue;
}
function fixEvent(event) {
    event.preventDefault = fixEvent.preventDefault;
    event.stopPropagation = fixEvent.stopPropagation;
    return event;
}
fixEvent.preventDefault = function() {
    this.returnValue = false;
};
fixEvent.stopPropagation = function() {
    this.cancelBubble = true;
};
Array.prototype.indexOf = function( obj ){
    var result = -1 , length = this.length , i=length - 1;
    for ( ;i>=0 ;i-- ) {
        if ( this[i] == obj ) {
            result = i;
            break;
        }
    }
    return result;
}
Array.prototype.contains = function( obj ) {
    return ( this.indexOf( obj ) >=0 )   
}
Array.prototype.append = function( obj , nodup ) {
    if ( !(nodup && this.contains( obj )) ) {
        this[this.length] = obj;
    }
}
Array.prototype.remove = function( obj ) {
    var index = this.indexOf( obj );
    if ( !index ) return ;
    return this.splice( index , 1);
};