You have been given the solution to remove all libs and reinstall, but in case a Gtk newbie is reading this, I would like to explain that the libs are dependent on an install order, and if you change/upgrade 1 library in that chain, all the librarys later in the chain must be recompiled/reinstalled. See Building Gtk , where the install order command is:
in reply to [SOLVED]: Issue with Glib1.261 & 1.260
build and install the GTK+ libraries in the order: GLib, Pango, ATK, then GTK+.
So that means if you change Glib, you need to rebuild Pango, ATK, and GTK+.