Registers a callback routine for a given widget.

widget — The widget ID of the widget to add the callback to (long).

reason — A string containing the callback reason. This parameter is GUI-dependent. See the Discussion section below for more information.

callback — A string containing the name of the callback routine.

client_data — A variable. The value of this variable is passed to the callback routine.

status — One (1) indicates success; zero (0) indicates failure.

Noparams — If present and nonzero, the callback is called with two parameters: wid and data. All other parameters, as discussed in Appendix B: Motif Callback Parameters in the PV‑WAVE Application Developer’s Guide.

Callback reasons are listed throughout the OSF/Motif Programmer's Reference.

To use a callback reason in PV‑WAVE, remove the XmN or XtN prefix. For example, the Motif callback reason XmNactivateCallback would become activateCallback.

The application can optionally use the client_data parameter to specify some application-defined data to be passed to the callback procedure when the callback is invoked. If client_data is a local variable (defined only in the current procedure), a copy of that variable is created and passed (passed by value). If the client_data is a global variable (defined in a Common Block), it is passed by reference.

This example creates a Motif button labeled Done. When you select the button, the widget is destroyed. To run the example, enter the callback and the example procedures in a file and run them with .RUN.

This is the callback routine. Note that the callback routine for the pushbutton widget class requires six parameters. The required callback parameters for Motif widget classes are discussed in Appendix A: Motif Widget Classes in the PV‑WAVE Application Developer’s Guide.

PRO CancelHelp, wid, data, npar, reason,  event, count

   COMMON block, top

   status=WtClose(top)

END

PRO example

   COMMON block, top

   @wtxmclasses.pro

   top=WtInit('wt_ex1', 'Examples')

   widget=WtCreate('Done', xmPushButtonWidgetClass, top)

   status=WtAddCallback(widget, 'activateCallback', $

      'CancelHelp')

   status=WtSet(top, /Realize)

   WtLoop

END

WwCallback