tv.oncheck = function(ID) {
	var o = this.getNode(ID);
	var v = o.checked;
	o.checked = document.getElementById("checkbox" + ID).checked;
	this.checkChildren(ID,o.checked);  //将该节点的子节点置为选中状态。
	this.checkParent(ID);//将该节点的父节点置为选中状态。
};

tv.checkChildren = function(ID,v){
	var ch = this.getNode(ID).childNodes;
	for(var i = 0;i<ch.length;i++){
		this.check(ch[i].ID,v);
		this.checkChildren(ch[i].ID,v);
	}
}

tv.checkParent = function(ID) {
	var par = this.getParentNode(ID);
	if(ID != this.getRoot(ID).ID){
		for(var j = 0;j<par.childNodes.length;j++)
			if(!par.childNodes[j].checked) break;
		this.check(par.ID,(j == par.childNodes.length));
		this.checkParent(par.ID);
	}
}

tv.check = function(ID,v){
	this.getNode(ID).checked = v;
	document.getElementById("checkbox" + ID).checked = v;
}