Describe the bug

Removal of block def. diagram removes also a relationship between block elements when Remove unused elements is switched off.

To Reproduce

Steps to reproduce the behavior:

1. Create a new BDD
2. Add two blocks
3. Create a composite association between them
4. The relationship is visible in the model
5. Delete the diagram
6. The relationship is removed

Expected behavior

Removal of a diagram shall not remove relationships (nor elements) when this mode is switched off.

Screenshots

Before:

After:

OS

• Linux (Ubuntu Latest)
• macOS
• Windows

Version

Version of Gaphor: 2.19.3

Additional information

Add any other context about the problem here.