How to trigger an event on filter / selection change in Workshop?

I have a filter or a string selector widget, and I separately have a function backing one of my variables. I’d like to recompute this function-backed variable only when a certain filter / string selector value changes. How to do that?

I wish the filter list and string selector widgets had Events available on changes similar to how buttons have Events available “On Click”. One workaround is to make the filter’s output or string selector’s output an input to the function. When I test this with a string selector, the function automatically updates when the string selector’s output changes.