function showBoxContent(box1,box2,box3) {
   if(document.layers)	{
	  fenster1 = document.layers[box1];
	  fenster2 = document.layers[box2];
	  fenster3 = document.layers[box3];
	}        // NC 4
   else if (document.all) {
	  fenster1 =  document.all[box1];
	  fenster2 =  document.all[box2];
	  fenster3 =  document.all[box3];
	}          // IE 4
   else if (document.getElementById) {
	  fenster1 = document.getElementById(box1);
	  fenster2 = document.getElementById(box2);
	  fenster3 = document.getElementById(box3);
	} // DOM
	if (fenster1.style.display == "") {
		fenster1.style.display = "none";
	}
	else {
		fenster1.style.display = "";
	}
	if (fenster2.style.display == "") {
		fenster2.style.display = "none";
	}
	else {
		fenster2.style.display = "";
	}
	if (fenster3.style.display == "") {
		fenster3.style.display = "none";
	}
	else {
		fenster3.style.display = "";
	}
}