function OnTreeClick(evt)
{
    var src = window.event != window.undefined ? window.event.srcElement : evt.target;
    var isChkBoxClick = (src.tagName.toLowerCase() == "input" && src.type == "checkbox");
    if(isChkBoxClick)
    {
        var parentTable = GetParentByTagName("table", src);
        var nxtSibling = parentTable.nextSibling;
        if(nxtSibling && nxtSibling.nodeType == 1)//check if nxt sibling is not null & is an element node
        {
            if(nxtSibling.tagName.toLowerCase() == "div") //if node has children
            {
                //check or uncheck children at all levels
                CheckUncheckChildren(parentTable.nextSibling, src.checked);
            }
        }
        //check or uncheck parents at all levels
        //CheckUncheckParents(src, src.checked);
    }
} 
function CheckUncheckChildren(childContainer, check)
{
  var childChkBoxes = childContainer.getElementsByTagName("input");
  var childChkBoxCount = childChkBoxes.length;
  for(var i = 0; i<childChkBoxCount; i++)
  {
    childChkBoxes[i].checked = check;
  }
}
function CheckUncheckParents(srcChild, check)
{
   var parentDiv = GetParentByTagName("div", srcChild);
   var parentNodeTable = parentDiv.previousSibling;
   
   if(parentNodeTable)
    {
        var checkUncheckSwitch;
        
        if(check) //checkbox checked
        {
            var isAllSiblingsChecked = AreAllSiblingsChecked(srcChild);
            if(isAllSiblingsChecked)
                checkUncheckSwitch = true;
            else    
                return; //do not need to check parent if any(one or more) child not checked
        }
        else //checkbox unchecked
        {
            checkUncheckSwitch = false;
        }
        
        var inpElemsInParentTable = parentNodeTable.getElementsByTagName("input");
        if(inpElemsInParentTable.length > 0)
        {
            var parentNodeChkBox = inpElemsInParentTable[0]; 
            parentNodeChkBox.checked = checkUncheckSwitch; 
            //do the same recursively
            CheckUncheckParents(parentNodeChkBox, checkUncheckSwitch);
        }
    }
}
function AreAllSiblingsChecked(chkBox)
{
 var parentDiv = GetParentByTagName("div", chkBox);
 var childCount = parentDiv.childNodes.length;
 for(var i=0; i<childCount; i++)
 {
    if(parentDiv.childNodes[i].nodeType == 1) //check if the child node is an element node
    {
        if(parentDiv.childNodes[i].tagName.toLowerCase() == "table")
        {
           var prevChkBox = parentDiv.childNodes[i].getElementsByTagName("input")[0];
          //if any of sibling nodes are not checked, return false
          if(!prevChkBox.checked) 
          {
            return false;
          } 
        }
    }
 }
 return true;
}
//utility function to get the container of an element by tagname
function GetParentByTagName(parentTagName, childElementObj)
{
  var parent = childElementObj.parentNode;
  while(parent.tagName.toLowerCase() != parentTagName.toLowerCase())
  {
     parent = parent.parentNode;
  }
return parent;    
}