// preload images
var imgBtnOver=new Image();
var imgBtnDown=new Image();
imgBtnOver.src="images/topbar-button-over.gif";
imgBtnDown.src="images/topbar-button-down.gif";
// buttons
function btnsetimg(id,img)
{
	var div=document.getElementById("btn"+id);
	div.style.backgroundImage="url("+img+")";
}
function btnover(id)
{
	btnsetimg(id,imgBtnOver.src);
}
function btnout(id)
{
	btnsetimg(id,null);
}
function btndown(id)
{
	btnsetimg(id,imgBtnDown.src);
}
function btnup(id)
{
	btnover(id);
}
function btnclick(href)
{
	document.location=href;
}