Comment 17 for bug 651678

I had the same problem with Inkscape in Maverick Meerkat after having installed the textext extension !
I use a Ubuntu server without Gnome/KDE/Xfce. I only use a light-weighted IceWM.
Here is the error i got :
Gtk:ERROR:gtkrecentmanager.c:1942:get_icon_fallback: assertion failed:
(retval != NULL)

I solved it in two times, first by creating the ~/.gtkrc-2.0 with a tango theme definition :
echo 'gtk-icon-theme-name="Tango"' >> ~/.gtkrc-2.0

And, as it was not sufficient, I also installed the corresponding theme :
sudo apt-get install tango-icon-theme

Now, everything is running fine.

By the way, I also got back the icons that I had lost in avidemux2_gtk after the Maverick Meerkat dist-upgrade...

Hope this helps.

Pour les francophones : la même explication détaillée ici :