IF use case element has only name, test is centered vertically.
But after user has added extension point, elements are not centered vertically
any more (it is connected to the top).


Steps to reproduce:

- Create a Use Case diagram
- Put a Use Case element on the diagram, name it 'Add Personal Information'
- Insert 'Add Birth Date' extension point to the Use Case
- enlarge use case element vertically.

name and extension point values are still connected to the top.
They should be centered vertically.