This was noticed on a Debian system. With kgtk-qt3-trinity installed
iceweasel, Etherape (possibly others) will not run :
Gtk-ERROR **: GTK+ 2.x symbols detected. Using GTK+ 2.x and
GTK+ 3 in the same process is not supported.
Trace/breakpoint trap
It is not known how it got on this particular system.
kgtk-qt3-trinity is mentioned in bug reports as being marked for removal
from TDE archives but is still there in 3.5.13.2
Adding this to /etc/apt/preferences blacklists it (create if it does not
exist):
Package: kgtk-qt3-trinity
Pin: origin ""
Pin-Priority: -1
David