DDX_Control
Visual Studio 2010
The DDX_Control function subclasses the control, specified by nIDC, of the dialog box, form view, or control view object.
void AFXAPI DDX_Control( CDataExchange* pDX, int nIDC, CWnd& rControl );
The pDX object is supplied by the framework when the DoDataExchange function is called. Therefore, DDX_Control should only be called within your override of DoDataExchange.
For more information about DDX, see Dialog Data Exchange and Validation.