Comment 8 for bug 790608

Sorry, I was a bit distracted the last week.

So.

Here is what I suggest as solution:
a) introduce a virtual package sound-theme-standard-freedesktop
b) have sound-theme-freedesktop and ubuntu-sounds provide the virtual package
c) have libcanberra depend on sound-theme-freedesktop | sound-theme-standard-freedesktop
d) have ubuntu-sounds provide empty foldersetup for freedesktop sounds (for sound installation by user and/or software)
e) seed ubuntu-sounds on ubuntu systems, thus providing the dependency as per c)

The advantage of this is: every installation that does not seed ubuntu-sounds or another "standard sounds covering" theme will end up with the standard freedesktop theme. Should a user uninstall ubuntu-sounds for whatever reason they will get the standard theme too (therefore ensuring that a user cannot accidentally break event sounds altogether).

Unresolved issues: if one were to install ubuntu, then install Xubuntu and Xubuntu where to use a different implementation of the spec this impl must depend on sound-theme-freedesktop to ensure it gets pulled in. An either or relationship as in canberra would not make sense as the impl would likely expect freedesktop to always be there (e.g. impl/xubuntu setting defaults to freedesktop sound theme, if that were not presented -> kaboom).

Additionally, since I am not quite sure how canberra stores the default theme. If it were to be stored in a way that would only set the default for on desktop, installing Ubuntu and then Kubuntu might result in broken sounds in latter as it is trying to use freedesktop whereas only ubuntu-sounds is installed. I don't think that is the case, but either way should be checked. Perhaps Colin could give input?