var fDesc=new Array();
fDesc[0] = "OpticalRayTracer is a free program that analyzes systems of lenses. It uses optical principles and a virtual optical bench to predict the behavior of many kinds of ordinary and exotic lens types. It allows the user to rearrange the optical configuration by simply dragging lenses around using the mouse.";

function tShowHide(id, show)
{
	var s = document.getElementById("desc");

	if ((s.innerHTML.length<=212 || show==1) && show!=2)
	{
		s.innerHTML = fDesc[id];
		if (document.getElementById('m1'))
			document.getElementById('m1').style.display='none';
		if (document.getElementById('m2'))
			document.getElementById('m2').style.display='none';
		if (document.getElementById('more_txt'))
			document.getElementById('more_txt').style.display='inline';
	}
	else
	{
		s.innerHTML = '';
	}
}