That sounds weird. Did you start from one of the sample applications, and if so, which one and what did you add to it and remove from it?
By the way, GoXam does not use any MessageBox, so that must be part of your application.
We used a bit from the StateChart demo, but mainly perhaps the “+” adorner. The quote I pasted before was not from a MessageBox but a bug report from someone who helped test. But yes, we have MessageBoxes to confirm if the user wants to delete each node or relation. I believe something triggers everything to be deleted, so we get a series of prompts, and when we try to cancel or perhaps when we complete all prompts, the entire diagram is gone.
Any common mistakes that would cause deletion of all diagram items? Any common technique used to delete all diagram items?
Other than performing the SelectAll and Delete commands, it isn’t clear to me what a user could do to naturally cause the deletion of everything. Particularly not while dragging around a node.
Check the stack at the time the MessageBox is shown. I wonder if the MessageBox is being shown at the proper time or event.
The normal way to prompt for approval of a user deletion is to implement a Diagram.SelectionDeleting event handler. Set the Handled property on the event args to cancel the deletion.
I’ll look into implementing that event handler, and let you know how it goes.