img01a=new Image();
img01a.src="img/but_1_a.gif";
img01=new Image();
img01.src="img/but_1.gif";
img02a=new Image();
img02a.src="img/but_2_a.gif";
img02=new Image();
img02.src="img/but_2.gif";
img03a=new Image();
img03a.src="img/but_3_a.gif";
img03=new Image();
img03.src="img/but_3.gif";
img04a=new Image();
img04a.src="img/but_4_a.gif";
img04=new Image();
img04.src="img/but_4.gif";
function on(graphName) {
    active=eval(graphName + "a.src");
	document.images[graphName].src=active;
}
function off(graphName) {
	dezact=eval(graphName + ".src");
	document.images[graphName].src=dezact;
}