Due to this check: https://github.com/glimmerjs/glimmer-vm/blob/10eae7429b702b1e7f5434b91802d5767ff7ad9a/packages/%40glimmer/util/lib/simple-cast.ts#L85 while appending an element [like this](https://developer.chrome.com/docs/web-platform/document-picture-in-picture#open_a_picture-in-picture_window) and then updating a tracked variable it relies on. Wondering why that check exists in the first place, and whether we can make it a bit more robust to allow this case. In my project I have simply patched out this line and it seems to work just fine.