I just started a jupyterhub server so that I can save all my data on one machine and have collaborators connect to access the data. Part of the code uses a GTK window which I normally launch from an ipython notebook. The error I get is TypeError: constructor returned NULL
(full traceback). I can pretty easily reproduce this by making a new notebook and running from matplotlib import pyplot
since by default it uses the GTK backend of my system.
So this works if I run it from the conventional jupyter-notebook and not through jupyterhub even if the notebook is accessed from the same computer that the server is running on. I recognize that many clients won't be able to load the GTK components if they don't have it installed themselves so I structured the software so that Gtk/Gdk only get imported when necessary. If I can't use it at all, though, then I will have to abandon the jupyterhub idea and think of something else.