var darkened_pics = new Array();
var lighted_pics = new Array();


function preloadButtonSet(num,dark,light) {
 darkened_pics[num] = new Image();
 darkened_pics[num].src = dark;
 lighted_pics[num] = new Image();
 lighted_pics[num].src = light;
}

preloadButtonSet(0,"images/home_off.gif","images/home_on.gif");
preloadButtonSet(1,"images/biography_off.gif","images/biography_on.gif");
preloadButtonSet(2,"images/qa_off.gif","images/qa_on.gif");
preloadButtonSet(3,"images/booklist_off.gif","images/booklist_on.gif");
preloadButtonSet(4,"images/awards_off.gif","images/awards_on.gif");
preloadButtonSet(5,"images/tips_off.gif","images/tips_on.gif");
preloadButtonSet(6,"images/magic_off.gif","images/magic_on.gif");
preloadButtonSet(7,"images/index_biography_off.gif","images/index_biography_on.gif");
preloadButtonSet(8,"images/index_qa_off.gif","images/index_qa_on.gif");
preloadButtonSet(9,"images/index_booklist_off.gif","images/index_booklist_on.gif");
preloadButtonSet(10,"images/index_awards_off.gif","images/index_awards_on.gif");
preloadButtonSet(11,"images/index_tips_off.gif","images/index_tips_on.gif");
preloadButtonSet(12,"images/index_magic_off.gif","images/index_magic_on.gif");

function lighten(num) {
 if (document.images)
  eval("document.button"+num+".src = lighted_pics["+num+"].src;");
 return false;
}
function darken(num) {
 if (document.images)
  eval("document.button"+num+".src = darkened_pics["+num+"].src;");
 return false;
}