function F_JS_showHide_given_id(JS_in_strlayerID)
{ 
if (document.getElementById(JS_in_strlayerID).style.visibility != "hidden")
   { 
    document.getElementById(JS_in_strlayerID).style.visibility = "hidden"; 
   } 
else
   { 
    document.getElementById(JS_in_strlayerID).style.visibility = "visible";
   } 
}