Example

The following lines create a menu button labeled Using Help... that calls the HelpRequestCB() function.

/* Create the ` Using Help ...' button. */

labelStr = XmStringCreateLtoR ("Using Help ...",           XmSTRING_DEFAULT_CHARSET);
 ac = 0;
 XtSetArg (al[ac], XmNlabelString, labelStr);     ac++;
 button = XmCreatePushButtonGadget (parent, "usingHelpButton", al,  ac);
    XtManageChild (button);
    XmStringFree (labelStr);
    /* Add a callback to the button. */
   XtAddCallback (button,XmNactivateCallback,HelpRequestCB,
    USING_HELP);

USING_HELP is the client data passed to the HelpRequestCB() function when the menu button is chosen by the user. Presumably it has been defined somewhere in the application (perhaps in a Help.h file) as a unique integer:

#define USING_HELP  47

To see how the HelpRequestCB() function handles the USING_HELP case, see the example in the next section, "To Display Help on Help."