Can't remove process diagram tab

Description of problem:

Environment: JBoss Developer Studio 8.1 with integration tooling.

When we add a new process diagram to a BPMN file in JBDS, then delete it, the tab for the new diagram is still visible.

Version-Release number of selected component (if applicable):
n/a

How reproducible:
always

Steps to Reproduce:
1.Create a new "jBPM process diagram";
2. Right click on the file, open with "Bpmn2 Diagram Editor";
3. Use JBDS menu, go to Diagram -> Create Process Diagram. Create it and save the file;
4. Close the diagram and open the file again now using Bpmn2 Model Editor and find the new diagram;
5. Right click on the diagram and delete it;
6. Finally reopen the file using the Bpmn2 Diagram Editor.

Actual results:

We can see a new tab called "Default Process".

Expected results:

No additional tab.

Additional info:
The attached video shows more details about how to reproduce it.