How to subscribe to a backend grid row action selection?

See the article: How is a row’s «Actions» dropdown implemented on the backend CMS pages grid?

Look closer at the function:

It attaches event handlers to a backend grid «Actions» dropdown.

Look deeper:

As you can see, you can set up a handler for an action wuth the callback key.

The core never uses this possibility for the grid «Actions» dropdown, but sometimes uses it for the adjacent «Edit» column to implement an inline row editing: