var create_menu = function(){
    var link = $('left_menu').childElements();
    for(var i=0;i<link.length;i++){
	var img = link[i].firstDescendant();
	img.id = 'left_menu_img_'+i;
	img.onmouseover= function(){show(this.id);};
	img.onmouseout= function(){hide(this.id);};
	var b = img.src.replace(/1\.jpg$/i,'2.jpg');
	link[i].setStyle({background:'url('+b+') scroll center'});
    };
    var link = $('right_menu').childElements();
    for(var i=0;i<link.length;i++){
	var img = link[i].firstDescendant();
	img.id = 'right_menu_img_'+i;
	img.onmouseover= function(){show(this.id);};
	img.onmouseout= function(){hide(this.id);};
	var b = img.src.replace(/1\.jpg$/i,'2.jpg');
	link[i].setStyle({background:'url('+b+') scroll center'});
    };
};
var flag = false;
var c;
var show = function(id){
    var cur_opacity = new Number($(id).getStyle('opacity'));
    //cur_opacity = cur_opacity.toFixed();
    if(c){c.cancel();};
    c = new Effect.Opacity(id,{duration:3.0,from:cur_opacity,to:0.0});
};
var hide=function(id){
    var cur_opacity = new Number($(id).getStyle('opacity'));
    if(c){c.cancel();};
    new Effect.Opacity(id,{duration:3.0,from:cur_opacity,to:1.0});
};
var run = function(id){
    var cur_opacity = new Number($(id).style.opacity);
    cur_opacity = cur_opacity.toFixed();
    if(flag == true){
	flag = false;
	new Effect.Opacity(id,{duration:3.0,from:0.0,to:1.0});
    }else{
	flag = true;
	new Effect.Opacity(id,{duration:3.0,from:1.0,to:0.0});
    };
};