if the packages you are having trouble installing are looking for a more recent version of glibc and you have already accepted that you will most likely have to reinstall; before doing so, try editing /etc/apt/sources.list and replace:
wheezy main contrib nonfree (just going off top of my head)
jessie main contrib
save then apt-get update and apt-get install whatever glib packages you need.
(you can be bold and try a apt-get upgrade and even more balls to the walls with a dist-upgrade)
if your distro is xfce, you might as well do: apt-get install xfce4 xfce4-goodies (this will upgrade your xfce4.8 to 4.10 and will also probly install more current glib packages.)
even if your distro is not xfce, i would recommend doing it anyways and changing your gnome-desktop to xfce.
if all your going to do is upgrade your glib packages from jessie repo, make sure your switch back to wheezy when your done.
there are more efficient ways of upgrading specific packages from sid and testing repositories, you might want to look into that.
please post any fixes/tips you come across.