Description of problem:
libvirt has explicit support for a few storage backends and they are managed as storage pools. However, the world is full of all sorts of disk access methods - loopback files, ata-over-ethernet drives, NBD drives, mmc devices, etc. Please allow specifying manually the explicit path to the disk to be used, so all of these can be supported by virt-manager without resorting to editing xml configurations.
This already works in the local case, provided the user has permissions to actually see the storage.
Proper fix is actually more managed storage usage :) Use directory pools to verify storage actually exists on the remote machine and possibly try and get format info about it, but do all this automatically. That way a user can enter an arbitrary path, and we use libvirt's storage enumeration to make sure it exists and has correct permissions, etc.
*** This bug has been marked as a duplicate of bug 557107 ***