It is a while since I did this, but what I do is the following. In a class derived from CFileDialog, I include the following in the declaration:

protected:
DECLARE_INTERFACE_MAP()
BEGIN_INTERFACE_PART(FileDialogControlEvents, IFileDialogControlEvents)
  STDMETHOD(OnItemSelected)(IFileDialogCustomize *, DWORD, DWORD);
  STDMETHOD(OnButtonClicked)(IFileDialogCustomize *, DWORD);
  STDMETHOD(OnCheckButtonToggled)(IFileDialogCustomize *, DWORD, BOOL);
  STDMETHOD(OnControlActivating)(IFileDialogCustomize *, DWORD);
END_INTERFACE_PART_OPTIONAL(FileDialogControlEvents)

Then in the source file, something like:

BEGIN_INTERFACE_MAP(CMyDialog, CFileDialog)
  INTERFACE_PART(CMyDialog, ID_IFileDialogControlEvents_MFC, FileDialogControlEvents)
END_INTERFACE_MAP()

in the constructor you need to include

USE_INTERFACE_PART_STD(FileDialogControlEvents);

you then need to implement the methods (the ones below are blank)

STDMETHODIMP CMyDialog::XFileDialogControlEvents::OnItemSelected( IFileDialogCustomize *pfdc, DWORD dwIDCtl, DWORD dwIDItem )
{
 METHOD_PROLOGUE(CMyDialog, FileDialogControlEvents)
 return S_OK;
}

STDMETHODIMP CMyDialog::XFileDialogControlEvents::OnButtonClicked( IFileDialogCustomize *pfdc, DWORD dwIDCtl )
{
 METHOD_PROLOGUE(CMyDialog, FileDialogControlEvents)
 return S_OK;
}

STDMETHODIMP CMyDialog::XFileDialogControlEvents::OnCheckButtonToggled( IFileDialogCustomize *pfdc, DWORD dwIDCtl, BOOL bChecked )
{
 METHOD_PROLOGUE(CMyDialog, FileDialogControlEvents)
 return S_OK;
}

STDMETHODIMP CMyDialog::XFileDialogControlEvents::OnControlActivating( IFileDialogCustomize *pfdc, DWORD dwIDCtl )
{
 METHOD_PROLOGUE(CMyDialog, FileDialogControlEvents)
 return S_OK;
}

STDMETHODIMP_(ULONG) CMyDialog::XFileDialogControlEvents::AddRef()
{
 METHOD_PROLOGUE(CMyDialog, FileDialogControlEvents)
 return pThis->ExternalAddRef();
}

STDMETHODIMP_(ULONG) CMyDialog::XFileDialogControlEvents::Release()
{
 METHOD_PROLOGUE(CMyDialog, FileDialogControlEvents)
 return pThis->ExternalRelease();
}

STDMETHODIMP CMyDialog::XFileDialogControlEvents::QueryInterface(
 REFIID iid, void FAR* FAR* ppvObj)
{
 METHOD_PROLOGUE(CMyDialog, FileDialogControlEvents)
 ENSURE(ppvObj != NULL);
 return (HRESULT)pThis->ExternalQueryInterface(&iid, ppvObj);
}

Look at the IFileDialogControlEvents interface for handling button clicks etc.

I'm not sure how you change from the default control size though....

• How can I better control the placement of the controls? E.g. if I wan to add a large edit field called Comments, I cannot control the size of it?
  My other question is about the events.
  
• Is there an easy way to overwrite the control events in MFC CFileDialog? In the MFC implementation I can see the the events are implemented, but how do I get access or overwrites then. E.g. the OnButtonClicked?

Thanks, cpede