With document.popupNode returning something similar during popupshowing, this is mostly fixed. There's one remaining issue with add-on items being re-added at the end of the popup repeatedly, but I'll file a new bug about that.
Bug 1700715 Comment 1 Edit History
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With document.popupNode returning something sensible during popupshowing, this is mostly fixed. There's one remaining issue with add-on items being re-added at the end of the popup repeatedly, but I'll file a new bug about that.