Hi Nadeem,
With regards to Application crashes while moving nodes on diagram, we are unable to reproduce the issue. We have created a simple and provide a video to represent this. Please refer to the sample and video from the attachment.
Testing Scenario:
In that sample , we have set the AllowSelect property to true for all nodes and Dragging the some Nodes over the DiagramPage.
If you feel still this issue exists, please get back us with simple sample to reproduce the issue.
Please let us know if you have any concerns.
Regards,
Ramya
AllowSelect (3)_93bb4895.zip