How to Read an Active X Control?

[Kannan]

My application is an MFC application but since MFC is essentially a
Object Oriented wrapper for Win32 I am taking the liberty to post my
question here. I also must confess that I am not an Active X
programmer.

Here is my problem:
I have to read a text string from a non editable TextBox in an "alien"
application. I say "alien" b'cas it is a third party application whose
source code is not available to me. The third party vendor tells me
that the non editable TextBox is implemented as an Active X Control.

The issues I have are as follows:
1. What must I do to get a handle (in MFC it would be a CWnd to the
ACTIVE X Control)?

2. I Don t believe that Spy++ lists all the Windows that I can
visually see in the target (i.e. third party) application. What are
the Windows that Spy++ will EXCLUDE in its Windows Hierarchy display.

3. Once I get a handle (in MFC - CWnd) to an Active X window I can get
the IUnknown to the Active X Control. Please let me know if this
understanding of mine is correct. The IUnknown can be obtained by any
one of the following calls:

LPUNKNOWN pUnk;
IUnknown *pi=0;
pUnk = localParentCWnd->GetControlUnknown();
If the ActiveX control is inside an ActiveX container then:
cmdTarg = (CCmdTarget *) localParentCWnd;
pUnk = cmdTarg->GetControllingUnknown();
If the ActiveX Container has native Windows controls inside it then:
HRESULT hr = AtlAxGetControl(localParentCWnd->m_hWnd,&pi);

Kannan