I have to give credit to DaveZ here, who uncovered an issue in the Kiosk browser (mentioned previously here) which allows the user to get out to a new window. That’s what I get for not really testing it myself much at all. (Although I will say that it’s possible to prevent this specific one if you only allow access to specific pages, and make sure those pages do not contain this vulnerability).
I will plan to fix this today, as well as a couple others I’ve uncovered on my own. I’ll let everyone know how it goes. When the new version is ready, anyone who wants to test it more (and finds a way to get “past it”) will be given credit in the app (along with DaveZ) as a “security tester”.