Summary:

SUBVBX is a sample appliction that does Windows subclassing on a VBX 
control using MFC 2.0.  The sample subclasses the grid control and 
overrides the OnDlgCode() message handler and returns the 
DLGS_WANTARROWS code.  Normally Windows uses the arrow keys to move 
between controls in a dialog box and does not pass the arrow keys to the 
control.  Subclassing the grid control and overriding the OnDlgCode() 
message handler causes windows to pass the arrow keys to the grid 
control so that it can use the keys to between cells in the control.

More Information:

Windows controls, such as an edit control or a listbox control, can be 
subclassed in MFC using the CWnd::SubclassWindow() and 
CWnd::SubclassDlgItem() functions.  These functions do not work for VBX 
controls.  These functions rely on the fact that each window control has 
its own windows procedure.  This way it is possible for an MFC object 
to chain to controls original Windows procedure.  However, VB controls 
under MFC 2.0 are managed by MFC objects.  So, VB controls use the same 
windows procedure as all other MFC objects.  

In order to subclass a VB control in MFC 2.0 it is necessary to copy the 
data from the original control object into the object that you want to 
use to subclass the original control.  After the original object has 
been copied, it can be detached and deleted, and the new control object 
can be attached.  

This sample defines the CVBClone class that contains the function 
SubclassVBControl().  This function does the copying, attaching and 
detaching that is described above.  To use this class, derive a new 
class from the CVBClone class and new message handling functions to the 
message map.  This class can then be used to subclass a VB control in a 
dialog box by calling the SubclassVBControl() function in the 
OnInitDialog() or OnInitialUpdate() function of the dialog box or form 
view that contains the control.  

This sample subclasses a grid control in a form view.  It defines the 
CMyGrid class from CVBControl which it uses to subclass the control.  It 
also calls SubclassVBControl in the OnInitialUpdate() of the form view 
to subclass the control in the form view.