function centerDiv(divId)
 {  
    document.getElementById(divId).style.left=((document.getElementById(divId).parentNode.offsetWidth/2)-(document.getElementById(divId).offsetWidth/2))+"px";
 }
 
 function toggleDivVis(divID)
 {
    document.getElementById(divID).style.visibility=(document.getElementById(divID).style.visibility=='visible' ? 'hidden':'visible');
 }
 function toggleDivDisp(divObj)
 {
    divObj.style.display=(divObj.style.display=='block' ? 'none':'block');
 }