/*
     * [Function]
     * un highlight tree node
     * [Input]
     * some TreeNode
     * 
     * [Output]
     * restore color to background color
     * 
     * [Note]
     */
    public Color unHighlightNode(TreeView trvValue, TreeNode treeNode)
    {
        Color oldColor = trvValue.BackColor;
        if (treeNode != null)
        {
            oldColor = treeNode.BackColor;
            treeNode.BackColor = trvValue.BackColor;
            treeNode.ForeColor = Color.Black;
        }

        return oldColor;
    }
    

            else if (e.ClickedItem == tsmiRemoveFromSelection)
            {
                if (curSelTreeNodeList.Contains(curSelTreeNode))
                {
                    //remove selection
                    curSelTreeNodeList.Remove(curSelTreeNode);

                    //unhightlight node
                    crl.unHighlightNode(trvCategoryTree, curSelTreeNode);
                }
            }