no, event listeners are canvas specific - they're for anything that should be clickable that IS a Canvas.
The GPSMap196 only happens to use those because it supports a "native" Canvas Window to render the whole instrument, i.e. without any cockpit at all.
This works by creating a background image and rendering another image with buttons on top of it, each button is associated with a SVG element ID.
That way, the whole thing works even without a cockpit (and even without an aircraft!).
I kind of prefer this generic approach - because it simplifies prototyping and testing significantly. Imagine being able to load & test your EFB with simple aircraft like the ufo/ogel etc - just by opening a dialog from the menu. That's what the GPSMap196 supports. So, the Nasal/Canvas code will basically open a few images and render them on top, and then associate the buttons with event listeners so that it can respond to events (the red screen is an embedded canvas created/managed elsewhere, so that the cockpit and the dialog can share the same "screen" output):
http://wiki.flightgear.org/Canvas_Glass_Cockpit_Efforts
Then again, for cockpit hot spots it uses actually a fairly inflexible and inelegant method through setting properties, so this is fairly low-level and not really needed IMO.
Unless you are planning to also create a skin with buttons, you won't need to use the Event Listener stuff, but it's documented here: http://wiki.flightgear.org/Canvas_-_Event_Handling
Personally, I'd directly associate Nasal callbacks with each button - but properties will work, too. Use what works best for you, and what you understand.
Canvas Event Listeners are really only useful in the context of a Canvas-based element.