BOOL pascal SetDlgItemStyle(HWND hDlg, int id, DWORD dwStyle)

  This function sets the 'Style' associated with a particular Dialog
   Item

Paramters
  hDlg is the handle to the dialog box.
  id is the identifier of the control within the dialog box.
  dwStyle can be WS_GROUP or any combination of WS_XXXX attributes. A
   radio button can have the WS_GROUP style. When a control has this
   style, it can be moved to by pressing the UP or DOWN arrow keys from
   within the dialog box.

Returns
  TRUE if id corresponded to a valid control, FALSE if not.