Get filter change event

I would like to save the configuration, including the selected filter values. I am already saving the configuration structure on “Apply” button. How can I get the event whenever a filter value is changed?

There is no special handler for such case.
You can use onBeforeRender event of pivot. Event will fire each time when pivot will repaint self, which means filters or configuration were changed.

$$("pivot").attachEvent("onBeforeRender", function(){
  //save config
});