function swap(Zielbild,Bildobjekt) {
  Zielbild.src = Bildobjekt.src;
}

mb01 = new Image();
mb01.src = "images/img/mbIcon1.gif";
mb01_on = new Image();
mb01_on.src = "images/img/mbIcon1_on.gif";

mb02 = new Image();
mb02.src = "images/img/mbIcon2.gif";
mb02_on = new Image();
mb02_on.src = "images/img/mbIcon2_on.gif";

mb03 = new Image();
mb03.src = "images/img/mbIcon3.gif";
mb03_on = new Image();
mb03_on.src = "images/img/mbIcon3_on.gif";