DevExpress XtraTreeList的复选框 禁用

private void treeListPer_CustomDrawNodeCheckBox(object sender, DevExpress.XtraTreeList.CustomDrawNodeCheckBoxEventArgs e)
{
//TreeListNode listNode = sender as TreeListNode;
if (e.Node.Tag.ToString()=="-1")
{
e.ObjectArgs.State = DevExpress.Utils.Drawing.ObjectState.Disabled;
}
}

private void treeListPer_BeforeCheckNode(object sender, DevExpress.XtraTreeList.CheckNodeEventArgs e)
{
if (e.Node.Tag.ToString() == "-1")
{
e.State = CheckState.Unchecked;
}
}