MFC如何修改文件视图FileView中已有的树结构的右键菜单（其相应函数为OnContextMenu），即如何增加/修改/删除 菜单项？

void CFileView::OnContextMenu(CWnd* pWnd, CPoint point)  //右键菜单
{
	CTreeCtrl* pWndTree = (CTreeCtrl*) &m_wndFileView;
	ASSERT_VALID(pWndTree);

	if (pWnd != pWndTree)
	{
		CDockablePane::OnContextMenu(pWnd, point);
		return;
	}

	if (point != CPoint(-1, -1))
	{
		// 选择已单击的项:
		CPoint ptTree = point;
		pWndTree->ScreenToClient(&ptTree);

		UINT flags = 0;
		HTREEITEM hTreeItem = pWndTree->HitTest(ptTree, &flags);
		if (hTreeItem != NULL)
		{
			pWndTree->SelectItem(hTreeItem);
		}
	}

	pWndTree->SetFocus();
	theApp.GetContextMenuManager()->ShowPopupMenu(IDR_POPUP_EXPLORER, point.x, point.y, this, TRUE);
}