[graph-tool] Gtk-WARNING

I am getting the following warning when using graph_draw: (process:23214): Gtk-WARNING **: Locale not supported by C library. Using the fallback 'C' locale. Dynamic session lookup supported but failed: launchd did not provide a socket path, verify that org.freedesktop.dbus-session.plist is loaded! Fontconfig warning: ignoring UTF-8: not a valid region tag It appears that the output file is still successfully rendered to .png. I am not sure what the implications of the warning are, how to remedy, or what, if anything, is affected by it? Thanks.