function openBackgroundLink()
{
		window.open( background_links[background], "", "height=400,width=300,scrollbars=no,dependent=yes,resizable=no")
/*	for ( i=0; i<backgrounds.length; i++) {
		if ( document.body.style.backgroundImage==backgrounds[i]) {
			window.open( background_links[i], "", "height=400,width=300,scrollbars=no,dependent=yes,resizable=no")
		}
	}
*/
}
var background;
var backgrounds=new Array()
backgrounds[0]="url(images/bg-tiling1.jpg)"
backgrounds[1]="url(images/bg-tiling2.jpg)"
backgrounds[2]="url(images/bg-fano.jpg)"
backgrounds[3]="url(images/bg-hailstone.jpg)"
backgrounds[4]="url(images/bg-macmahon.jpg)"
backgrounds[5]="url(images/bg-simtriangles.jpg)"
backgrounds[6]="url(images/bg-star.jpg)"
backgrounds[7]="url(images/bg-ulam.jpg)"
var background_links=new Array()
background_links[0]="abouttiling1.html"
background_links[1]="abouttiling2.html"
background_links[2]="aboutfano.html"
background_links[3]="abouthailstone.html"
background_links[4]="aboutmacmahon.html"
background_links[5]="aboutsimtriangles.html"
background_links[6]="aboutstar.html"
background_links[7]="aboutulam.html"

function chooseBackground()
{
		var d;
		d = new Date();
		background = d.getMilliseconds() % backgrounds.length;
		document.body.style.backgroundImage = backgrounds[background];
}