var lastclick = new Image();

function dn(imgname) // on mouseover
 { imgname.src = imgname.src.replace(/rot/,"gruen") 
 }	      

function up(imgname) // on mouseout
 { if ( imgname != lastclick )
     { imgname.src = imgname.src.replace(/gruen/,"rot") }
 }	      

function clck(imgname) // den eigenen lastclick zurücksetzen
 { if ( lastclick != imgname ) 
     { if ( lastclick) lastclick.src = lastclick.src.replace(/gruen/,"rot");
       lastclick = imgname;	 
	 }     	 
   window.focus();	
 }	      

function preload()
 { var i, im;
	for ( i = 0; i < document.images.length; i++ )
	  { if ( document.images[i].src.match(/rot/) )
	      { im = new Image();
  	        im.src = document.images[i].src.replace(/rot/,"gruen");
  		  }
	  }
 }