function zeige(id) {
  if (document.getElementById) {
  document.getElementById(id).style.display="block";
} else if (document.all) {
  document.all[id].style.display="block";
} else if (document.layers) {
  document.layers[id].display="block";
} } 

 function verberge(id) {
  if (document.getElementById) {
  document.getElementById(id).style.display="none";
} else if (document.all) {
  document.all[id].style.display="none";
} else if (document.layers) {
  document.layers[id].display="none";
} }

function flip_helpbook ()
	{
  	if (document.getElementById("helpbook").style.visibility == "visible")
       	{
    	document.getElementById("helpbook").style.visibility = "hidden";
        document.getElementById("u_status").src="pics/plus.gif";
        }
	else
    	{
    	document.getElementById("helpbook").style.visibility = "visible";
        document.getElementById("u_status").src="pics/minus.gif";
        }
    }