API to detect that a visualization is closing

We created some custom visualizations that add calculated columns to the source data table. When we close the visualization, we would like to drop the added columns.

We are looking for an API that is invoked when the visual is closing/closed.

So that we use it to add our custom code to cleanup the table once the visual is closed. We tried using the destructor of the class, but this depends on the garbage collector ... and may take few minutes before being called.

So the request is to add a new API in Spotfire that is invoked when a visual is closing or closed?

Workarond: I need to listen to all visuals in all pages to detect a change then try to guess what visual is closed since this requires caching some info about the opened visualizations.