Child Tree - all descendants of a node

	// Walk Tree of All Descendants
	
	// Used to build multi-select list of hierarchy for selecting a template variable
	
	$ic = 0;
	$depth = array();
	$idepth = 0;
	$c = array();
	$bDone = false;
	$o = '';

	// parameter: &docid=root document of tree
	if (!$docid) { return ''; }
	
	// do we just build array
	// or process and not leave tracks?

	// $c array is children id's and values ($ic is index)
	// $depth array is index to current level item while we're traversing ($idepth is index)
	// 		used for backtracking
	$c[$idepth] = array( array("id" => $docid, "pagetitle" => "root") );
	$depth[$idepth] = 0;
	
	while (!$bDone)	{
		$thisid = $c[$idepth][$ic]["id"];
		$pg = $c[$idepth][$ic]["pagetitle"];
		
		if ($thisid != $docid)	{		// don't process root node
			// process this node
			for ($i=1; $i<$idepth; $i++)	{
				$o .= "-";
			}
			$o .= "$pg==$this||";
		}
		
		$a = $modx->getDocumentChildren($thisid,1,0,'id,pagetitle');
		if ($a)	{
			// yes children, descend
			$depth[$idepth] = $ic;		// hold current position for continuing
			$idepth++;					// down one
			$c[$idepth] = $a;			// store this level's siblings
			$ic=0;						// start at first child
			$depth[$idepth] = $ic;		// current level's position
		}
		else	{
			$ic++;	// next sib
		}
		
		while (!$bDone && $idepth && !isset($c[$idepth][$ic]))	{
			// no element here, go up
			$idepth--;
			if ($idepth)	{
				$ic = $depth[$idepth];		// last parent
				$ic++;						// next sib
			}
			else	{
				$bDone = true;
			}
		}
	}
	return $o;