I add two editbox to CXTPTabControl!
When I use DeleteAllItems() to remove all editbox in CXTPTabControl.
There still editbox exist in tabcontrol.

I check the code and find the reason:
CXTPTabManagerItem does nothing for its m_hWnd in destructor.
That means, all window added to XTPTabControl must be destroyed manually.

So I add as below
CXTPTabManagerItem::~CXTPTabManagerItem()
{
 if(IsWindow(m_hWnd))
 {
  DestroyWindow(m_hWnd);
  m_hWnd = NULL;
 };
}
So that CXTPTabManager::DeleteItem() and DeleteAllItems() would destroy the child window as I need.

But another problem prompt:
I used a CXTPTabClientWnd
In function UpdateContents()
There is the line:
   pFoundItem->Remove();
When call this, the found CXTPTabManagerItem's window(i.e, childwindow) will be destroyed by  CXTPTabManager::DeleteItem();

While another line in UpdateContents() is :
   pChildWnd = pChildWnd->GetWindow(GW_HWNDNEXT);
when the pChildWnd->m_hWnd is destroyed, this function would be turned into assert failure!

(That is, the last childframe of multidoc app is closing, you will catch the failure)

How can I solve this?

I reffer to CXTTabCtrl:
And find there is DeleteItem(nItem, BOOL bDestroyWnd);

So the better modification of CXTPTabContorl is the same like CXTTabCtrl?
Use the parameter bDestroyWnd to let user select to destory the window?

Don't modify CXTPTabManagerItem in same way.

CXTPTabControl have no idea do you want destroy or hide child panes if they closed so you must manually Destroy them. (There are a lot of situations when developer don't want to destroy them).