I have a GUI application written in python, that uses GTK and runs on Ubuntu, and it has been working well for many months.
The GTK application uses gtk.Builder() and a Glade input file (a user interface designer for GTK+ and GNOME).
When launching the application from the console, the following error is printed:
(evms.py:14241): Pango-CRITICAL **: 08:17:31.288: pango_attr_gravity_new: assertion 'gravity != PANGO_GRAVITY_AUTO' failed
(evms.py:14241): Pango-CRITICAL **: 08:17:31.288: pango_attr_gravity_new: assertion 'gravity != PANGO_GRAVITY_AUTO' failed
Then the app proceeds to run (and print output to the console) however the GUI window itself isn't ever displayed.
I posted about this in a separate question yesterday but it hasn't received a response, so I'm trying a different description of the issue.
This issue has been resolved.
The PANGO critical error still occurs and I'm not sure what that issue is about.  However, that error wasn't responsible for GTK not launching the GUI window.  The GUI launching issue was due to a thread that wasn't functioning properly, due to a naming mistake.
GTK app written in python with glade fails to launch its GUI