I created a VM on a 3 gigabyte disk file.
File> Restore Virtual Machine> Selected the disk file.
virt-manager deletes it.
The 'restore' menu options isn't for starting inactive domains, its actually for
restoring guests that have previously been suspended (aka hibernated/saved). So
it is not expecting a raw disk image, but instead a VM suspend image. That said
it ought to have detected that you supplied a bogus image & refused to proceed,
rather than deleting it.
It's amazing that it deleted it.
Maybe the restore option could be more explicit too.
I had powered off a VM and wanted to run it again. I presumed that was right.
This is now fixed with validation that the image we are trying to get xen to
restore is in fact a valid Xen Paravirt image.