CreateControl too "early"

I'm a noob to MFC, and a noob to this site

I'm trying to add a windowless active X control to a CWnd dialog.

The problem is, if I attach my control during OnInitDialog, the control is later detached via COleControlSite:etachWindow, and is therefore not shown.
I can get it to work by creating my control later, when the parent control is getting a WM_SIZE message for the second time...but this is really hacky and I don't understand it.

So...the below code works, but I'd rather not have the hack / understand what's going on

Code:

CParentControl::CParentControl()
{
     m_pChild = NULL;
}

void CParentControl::OnInitDialog()
{
     // This is successful, but Windows detaches the control soon after
     CreateChild();
}

LRESULT CParentControl::OnSize (UINT uMsg, WPARAM wParam, LPARAM lParam, BOOL& bHandled)
{
     if (!m_pChild)
     {
          if (lParam == 0)
          {
               // This is successful, but Windows detaches the control soon after
               CreateChild();
          }
          else
          {
               // This works, and creates a permanent control! But why?
               CreateChild();
          }
     }
}

void CreateChild ()
{
     CWnd * me = CWnd::FromHandle(m_hWnd);

     // This always returns a success code...
     BOOL ret = m_pChild->CreateControl( clsid, NULL, WS_VISIBLE|WS_CLIPCHILDREN|WS_CLIPSIBLINGS, CRect(10,10,300,300), me, 0);
}

 

Obviously [noparse]"COleControlSite:etachWindow" [/noparse]should be

Code:

COleControlSite::DetachWindow

 

Got it working by using a second wrapper (an activeX control). The code for adding the child control then, looks like this:

Code:

void CreateChild ()
{
	m_axWnd.reset(new CAxWindow());	
	if (!m_axWnd.get()) 
	{
		return;
	}

	CRect rc;
	GetClientRect(&rc);
	m_axWnd->Create(m_hWnd, rc, NULL, WS_CHILD|WS_VISIBLE);
	
	_bstr_t clsStr = my_CLSID;
	m_axWnd->CreateControl(clsStr);		
}

...and the control can be added OnInitDialog and it will be persistent.