CTreeCtrl选取一个Item以后如何让它失去被选中状态

Question

想在OnSelChanged中做些操作，所以必须在选择一个Item后让它失去被选中状态，不然下次接着选这个Item将无效。我用SelectItem(NULL)让它失去选中状态，结果发现SelectItem(NULL)后变成RootItem成为被选中状态了，难道必须有一个Item成为选中状态吗该怎么办呢

Answer 1

没有问题啊，我用一个按钮试的，tree属性设为show selection always
#define MAXTEXTLEN 50HTREEITEM GetItemByName(HWND hWnd, HTREEITEM hItem, 
                        LPCTSTR szItemName)
{
    // If hItem is NULL, start search from root item.
    if (hItem == NULL)
        hItem = (HTREEITEM)SendMessage(hWnd, TVM_GETNEXTITEM,
                                       TVGN_ROOT, 0);
    while (hItem != NULL)
    {
        char szBuffer[MAXTEXTLEN+1];
        TV_ITEM item;        item.hItem = hItem;
        item.mask = TVIF_TEXT | TVIF_CHILDREN;
        item.pszText = szBuffer;
        item.cchTextMax = MAXTEXTLEN;
        SendMessage(hWnd, TVM_GETITEM, 0, (LPARAM)&item);        // Did we find it?
        if (lstrcmp(szBuffer, szItemName) == 0)
            return hItem;        // Check whether we have child items.
        if (item.cChildren)
        {
            // Recursively traverse child items.
            HTREEITEM hItemFound, hItemChild;            hItemChild = (HTREEITEM)SendMessage(hWnd, TVM_GETNEXTITEM,
                                                TVGN_CHILD, (LPARAM)hItem);
            hItemFound = GetItemByName(hWnd, hItemChild, szItemName);            // Did we find it?
            if (hItemFound != NULL)
                return hItemFound;
        }        // Go to next sibling item.
        hItem = (HTREEITEM)SendMessage(hWnd, TVM_GETNEXTITEM,
                                       TVGN_NEXT, (LPARAM)hItem);
    }    // Not found.
    return NULL;} 
void CGhghfDlg::OnButton1() 
{
HTREEITEM hItem = GetItemByName(m_tree.GetSafeHwnd(),
                                    NULL, "111");
    if (hItem != NULL)
        m_tree.SelectItem(hItem);}void CGhghfDlg::OnButton2() 
{
m_tree.SelectItem(NULL);
}

Answer 2

tree有没有“必须有一个被选中”的属性？