Comment 11 for bug 95394

Alex, you can hold a package to avoid upgrading it with aptitude (and apt-get I suppose)

In example, if you don't want to upgrade beryl, type:
# sudo aptitude hold beryl

Remember, when you want to upgrade it you can unhold it and upgrade OR just install it:
# sudo aptitude unhold beryl
# sudo aptitude install beryl

To know if there is a newer version, you can check your system's version and the repo's one with:
$ apt-cache policy beryl