[libvirt] arbitrary qemu command feature

[Bruce Hohl]

Hello List, I had a problem with the recently added qemu command
feature (no one on user list could help):

This feature:
http://libvirt.org/news.html
0.8.3: Aug 4 2010
Improvements:
Handle arbitrary qemu command-lines in qemuParseCommandLine.
Qemu arbitrary command-line arguments.

Also described here:
http://www.spinics.net/linux/fedora/libvir/msg26687.html
[PATCH v4 0/8]: Add arbitrary qemu command-line and monitor commands

I am using the following libvirt 0.8.3 packages from unbuntu 10.10:
libvirt-bin 0.8.3-1ubuntu14
libvirt0 0.8.3-1ubuntu14
python-libvirt 0.8.3-1ubuntu14

Example of problem: "$ virsh edit my.xml" refuses to add / will not
save the following to a domain (for this domain graphics type='sdl')
using the specified format:

<qemu:commandline>
  <qemu:arg value='-ctrl-grab'/>
</qemu:commandline>

If I edit and save the xml directly the change is not recognized upon
start-up of the domain.  That is, I must use ctrl+alt instead of the
right ctrl for mouse capture.

Am I missing a library or package needed? Am I using this feature
correctly? Is there a working example or additional documentation
somewhere? Any suggestions?