When I try to run a python application which uses a pyplot-window, I get a warning in the command line:
Gtk-Message: Failed to load module "pantheon-filechooser-module"
How can I fix it, and what causes it?
Pantheon Files (the default file manager) contains a custom GTK+ module called
It's shipped on up-to-date systems, but it's not activated yet (currently, the default GTK+ file chooser dialog is still in use). That's most likely the reason it fails to load. Additionally, it might fail because it is a GTK+2 application.
On the other hand, it might be possible you removed Pantheon files. If that's the case, it might be the (other) reason the module fails to load, because it's not installed on your system.