Hello,
I maintain gmpc, from the same upstream author.
The version in testing builds only with vala-0.16 which is scheduled
for removal. This would leave gmpc RC-buggy (see #739030).
As a solution I would like to introduce a newer version, probably a
git snapshot. The problem is that it needs a recent libmpd version. No
release has been officially made but everything works with the latest
upstream commit from 2013-03-19.
I see that you're in the Low NMU threshold, if you want I can do the
work as part of a NMU, but as it is quite disruptive I prefer to ask
you first.