Expand child process for a call activity in the visual editor

I have been fooling around with the modeler and am trying out the call activity.

I create the child element first and name it.
I then create the parent that calls the child.

The image presented on the overall process view page on http://localhost:8080/flowable-modeler/#/processes
shows the parent calling the child element with the '+' on the call activity. However if I click into the parent process visual editor, the call activity just looks like every other task. I am not able to expand it to see the child contents. I would have to back out and look at the child separately.

Stems from a forum posting:

http://forum.flowable.org/t/flowable-ui-getting-started/205/3

Flowable Modeler のプロセスビジュアルエディターで、子要素と親の call activity を作成して問題を再現します。プラス記号のマーカーが表示されるプロセス概要と親エディターを比較し、call activity がどのようにレンダリングされ、開かれるかを追跡します。完了の条件は、親エディターでユーザーが call activity を展開し、子要素の内容を表示できることです。

索引モデルが issue の本文から書いたものです。