function show(cover,id){
	var objCover=document.getElementById(cover);
	var objId=document.getElementById(id);
	var scrollW=document.documentElement.scrollWidth;
	var scrollH=document.documentElement.scrollHeight;
	var T=(document.documentElement.clientHeight-objId.clientHeight)/2+document.documentElement.scrollTop;
	var L=(document.documentElement.clientWidth-objId.clientWidth)/2+document.documentElement.scrollLeft;
	objCover.style.width=scrollW+"px";
	objCover.style.height=scrollH+"px";
	objCover.style.visibility="visible";
	objCover.style.display = "block";
	objId.style.top=T+"px";
	objId.style.left=L+"px";
	objId.style.visibility="visible";
	objId.style.display = "block";
}
function hide(cover,id){
	var objCover=document.getElementById(cover);
	var objId=document.getElementById(id);

	objCover.style.visibility="hidden";
	objId.style.visibility="hidden";
	objCover.style.display = "none";
	objId.style.display = "none";
}