function preload(imgs){
 for(var i = 0; i < imgs.length; i++){
   var imgObj = new Image();
   imgObj.src = imgs[i];
 }
}

preload(["img/common/menu_r1_c1.gif","img/common/menu_r1_c2.gif","img/common/menu_r1_c3.gif","img/common/menu_r1_c4.gif","img/common/menu_r1_c5.gif","img/common/menu_r1_c6.gif"]);
preload(["img/common/menu_r2_c1.gif","img/common/menu_r2_c2.gif","img/common/menu_r2_c3.gif","img/common/menu_r2_c4.gif","img/common/menu_r2_c5.gif","img/common/menu_r2_c6.gif"]);

function menuchg(obj,pic){
	obj.src='img/common/'+pic;
//	alert(img/common/'+pic);
}

function menuret(obj,pic){
	obj.src='img/common/'+pic;
}