function createCookie(name,value,days) {
	if (days) {
		var date = new Date();
		date.setTime(date.getTime()+(days*24*60*60));
		var expires = "; expires="+date.toGMTString();
	}
	else var expires = "";
	document.cookie = name+"="+value+expires+"; path=/";
}

function readCookie(name) {
	var nameEQ = name + "=";
	var ca = document.cookie.split(';');
	for(var i=0;i < ca.length;i++) {
		var c = ca[i];
		while (c.charAt(0)==' ') c = c.substring(1,c.length);
		if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
	}
	return null;
}
function set_wallpaper() {
	var what = readCookie('vl_wallpaper');
	if( what == null ) what = Math.ceil(Math.random()*7);
	document.body.id ='wallpaper' + what;
	
	var current_thumb = document.getElementById( 'thumbnail_' + what );
	if( current_thumb ) current_thumb.style.border = '1px solid #aaa';
}

function changebackground(myButton, myNumber) { 
    createCookie('vl_wallpaper',myNumber,700);

	current_thumb = document.getElementById( 'thumbnail_' + myNumber );
	if( current_thumb ) current_thumb.style.border = '1px solid #ddd';
	myButton.style.border = '1px solid #aaa';
    document.body.id ='wallpaper' + myNumber;
}