message: add ability to set onVisibleChanged in definition:
diff: @@ -148,6 +148,9 @@ export class Survey extends React.Component<any, any> implements ISurveyCreator
  if (newProps.data) newProps.data[options.name] = options.value;
  if (newProps.onValueChanged) newProps.onValueChanged(sender, options);
  });
  + if(newProps.onVisibleChanged) {
  + this.survey.onVisibleChanged.add((sender) => { newProps.onVisibleChanged(sender); });
  + }
  if (newProps.onComplete) {
  this.survey.onComplete.add((sender) => { newProps.onComplete(sender); });
  }
  