When using toggle buttons, there are times when it would be nice to
have the layout flexibility of an XmForm or XmpTable widget.  However,
if you use any other manager than a XmRowColumn, you don't get the
XmNradioBehavior resource to ensure that one and only one button stays
pressed at once.  The EnforceRadioBehaviorCB() callback in radioCB.c is a
XmNvalueChanged callback that can be placed on every toggle button in
the manager.  This callback will then enforce the radio style behavior
on every toggle button widget or gadget child of the manager.

Note that when the toggle buttons are created with a non-XmRowColumn
parent, you must create them with the XmNindicatorType set to
XmONE_OF_MANY.  The XmRowColumn usually does this for you
automatically.

The enclosed program demonstrates this by creating a dummy interface
composed of a form with some toggle button children and a pushbutton.
This particular interface could have been created with a XmRowColumn
widget, but the intent was to make it simple enough to illustrate the
point.

I've used this callback on both X11R5/Motif 1.2.

-Greg Ullmann