GetCRefCon
GetCRefCon Query control's reference value
#include <Controls.h> Control Manager
long GetCRefCon(theControl );
ControlHandle theControl ; handle of the control to update
returns The current value of (* theControl)->contrlRfCon
GetCRefCon returns the current value of the "reference constant" of a
control.
theControl is a handle leading to a variable-length ControlRecord structure. It
specifies which control to query.
Returns: a 4-byte long; the current value in the contrlRfCon field of
theControl's ControlRecord structure.

Notes: GetCRefCon returns the "reference constant" of the theControl. It is
functionally equivalent to:
long curRefCon;
curRefCon = (* theControl )->contrlRfCon;
The reference constant can be useful in identifying controls, especially to
make sure the GetNewControl returned the control you expected and for
controls identified as items in a dialog (see GetDItem).
The field is set originally when the control is created (see NewControl)
and is not modified by the system. You can use SetCRefCon to change it;
thus it can be used for keeping track of control-related information which
is not otherwise maintained in the ControlRecord.