Mutation observer class observes changes in the DOM, fires
event-mutationsevent, mark view elements as changed and call
render. Because all mutated nodes are marked as "to be rendered" and the
renderis called, all changes will be reverted, unless the mutation will be handled by the
event-mutationsevent listener. It means user will see only handled changes, and the editor will block all changes which are not handled.
Mutation item for child nodes.
Mutation item for text.