How to detect that a TVML lockup loses focus?

Is there a way to detect that a lockup loses focus when using TVML and TVMLKit JS on tvOS 12?

I know there's a highlight event when an element receives focus using the following:

lockupElement.addEventListener("highlight", this.handleHighlight);

I want to handle when the lockup is no longer highlighted. The closest I've found to a solution is to add highlight-events to absolutely every other element and then reset any previously highlighted elements. This seems like a hack and it is also tedious and bug-prone.

Anyone know of a better method?