When you click an element's (ev) event bubble in the inspector, that gives you the list of event listeners attached to this element. Chrome DevTools also has a useful way to show ancestors' listeners too (which would be triggered too when the event bubbles up). This is a feature request to add this. Now, Chrome has this in a sidebar panel, while it's all in a popup in Firefox. This does make it a little more complicated to add UI to it to toggle the ancestors listeners I suppose.

This feature is planned as part of "Pause on Event" project. You might also see: https://docs.google.com/document/d/1HPTnwnYydsRBRZw3XqGoiOSaMSIeHBvKRQENm4RegPI/edit?ts=5bce6279#heading=h.532o8ksi95wv Honza

Duplicate of bug 991174? Sebastian

Yep, done, thanks! Honza