message: Fix EditorModel clone to actually be useful
diff: @@ -91,7 +91,8 @@ export default class EditorModel {
  }
  public clone(): EditorModel {
  - return new EditorModel(this._parts, this._partCreator, this.updateCallback);
  + const clonedParts = this.parts.map(p => this.partCreator.deserializePart(p.serialize()));
  + return new EditorModel(clonedParts, this._partCreator, this.updateCallback);
  }
  private insertPart(index: number, part: Part): void {
  