Describe the bug

sub package will disaper when draging parent package insert under to sub package

To Reproduce

Steps to reproduce the behavior:

1. create package
2. create sub package under package
3. create some diagrame
4. drag package under sub package
5. sub package will disapper

if save file and reopen file subpackage will appear again

Expected behavior

Do not allow parent dragging to child or refresh button to redraw the tree

Screenshots

OS

• Windows

Version

Version of Gaphor: 2.24.0

Additional information