We don’t actually have a working undo yet (which is kind of crazy!).
However, if you enter a text-field and edit this, by accident or choice, you can either commit the change by hitting Enter, clicking outside or the field or by zooming out. Alternatively you can hit “Esc” to cancel the change.
An error occurred while saving the firstname.lastname@example.org commented
That is crazy. Being new at this I have already hit Ctrl+Z too many times now not to be a bit annoyed. Necessary command.