menueitem = "undefined";

b2_on = new Image(30,195);
b5_on = new Image(30,195);
b8_on = new Image(30,195);
b1_on = new Image(30,197);
b4_on = new Image(30,197);
b7_on = new Image(30,197);
b3_on = new Image(30,197);
b6_on = new Image(30,197);
b9_on = new Image(30,197);
gtgs_on = new Image(8,81);

b2_off = new Image(30,195);
b5_off = new Image(30,195);
b8_off = new Image(30,195);
b1_off = new Image(30,197);
b4_off = new Image(30,197);
b7_off = new Image(30,197);
b3_off = new Image(30,197);
b6_off = new Image(30,197);
b9_off = new Image(30,197);
gtgs_off = new Image(8,81);

b2_on.src = "img/2a.gif";
b5_on.src = "img/5a.gif";
b8_on.src = "img/8a.gif";
b1_on.src = "img/1a.gif";
b4_on.src = "img/4a.gif";
b7_on.src = "img/7a.gif";
b3_on.src = "img/3a.gif";
b6_on.src = "img/6a.gif";
b9_on.src = "img/9a.gif";
gtgs_on.src = "img/gtg_a.gif";

b2_off.src = "img/2n.gif";
b5_off.src = "img/5n.gif";
b8_off.src = "img/8n.gif";
b1_off.src = "img/1n.gif";
b4_off.src = "img/4n.gif";
b7_off.src = "img/7n.gif";
b3_off.src = "img/3n.gif";
b6_off.src = "img/6n.gif";
b9_off.src = "img/9n.gif";
gtgs_off.src = "img/gtg_n.gif";

function switch_img(img_off,img_on)
 {
  if(menueitem != img_off)
   {document.images[img_off].src = eval(img_on + ".src");}
 }