function event_add(target,event,func)
{
	if(target.addEventListener){
		target.addEventListener(event,func,false);
	}
	else if (target.attachEvent){
		target.attachEvent("on"+event,func);
	}
	else{
		alert("event_add error");
	}
}
	
function event_remove(target,event,func)
{
	if(target.removeEventListener){
		target.removeEventListener(event,func,false);
	}
	else if (target.detachEvent){
		target.detachEvent("on"+event,func);
	}
	else{
		alert("event_remove error");
	}		
}