Steps to reproduce:

• create a new Bpmn 2.0 Diagram
• add a pool to the diagram (resize the pool: make it bigger)
• add the pool the following elements (start event -> sub process -> end event)
• resize the subprocess (make it bigger)
• save the diagram
• close the diagram
• reopen the diagram

-> The pool has not the correct size (the DI-Informations are not saved correctly)