function loadImages() {
   var buttons=new Array(4);
   for (i=0;i<4;i++) buttons[i]=new Image();
   buttons[0].src="/gfx/button-home-gelb.gif";
   buttons[1].src="/gfx/button-login-gelb.gif";
   buttons[2].src="/gfx/button-karte-gelb.gif";
   buttons[3].src="/gfx/button-suchen-gelb.gif";
}

function toggleButton(img, state1, state2) {
   var file,l,type,i;
   file = img.src; l = file.length; type = file.substring(l-3,l);
   i = file.indexOf(state1); if (i>0) {
      img.src=file.substring(0,i)+state2+type;
   }
   return true;
}

function mouseOver(img) { return toggleButton(img,"-grau.","-gelb."); }
function mouseOut(img)  { return toggleButton(img,"-gelb.","-grau."); }