Sorry for the delay in answering. Here is the solution, and it works very well.
Each Button on the Button Bar must be given a name, if not it will not work. See this screen capture
- The top button on the bar is selected
- In the the left most Tab of the Inspector, the Object name of this button, not what the button displays, is set.
- In the Objects Tab of the left pane in Layout mode, the name is displayed. If something else is displayed, the the button Name is not set, and it will not be possible to programatically set the active button.
One more setting is needed on the Button Bar properties
The Active Segment is specified in this field. Note the value is Specify.... Lets see what the PopupMenu choices are
Click on Specify... and
we have the Specify Calculation window ! I use a global variable that is set to the name of the specific button, for example "SE01". And that's it !