Take a look at the "Audio" diagram in the XMI pointed to in the bug URL. When you first open it the diagram, there are a few items on the far left side of the canvas at various positions. If you click on them and drag only a pixel or two, they snap back to where they were suppose to be. 

The three boxes farthest from the right are also way too far out. I move them back left more into the diagram.

When I save the diagram and open it back up again, both of these problems are reverted back as though I hadn't done anything.

Reproducible: Always

Steps to Reproduce:
1. Open the URL in Umbrello svn head.
2. Open the Audio diagram.
3. Snap the objects on the far left back to where they came from.
4. Move the boxes on the far right back closer into the diagram.
5. Save.
6. Re-open.
7. Both problems back as they were before.