User blog comment:MisterWoodhouse/The Future of Gamepedia/@comment-5078732-20201110183023/@comment-39885705-20201111021714

4. PROBLEM! You also can't cancel the edit, either. The screen will be frozen until you hit your browser's Back button and start over.

UCP's editor is probably one of the worst in the history of humanity. I think punchcards were easier.