clean up tests and folders

tests/mpltest.py

@@ -0,0 +1,23 @@
+#!/usr/bin/env python3
+import os
+import sys
+
+# 1) force GTK3 backend *before* pyplot is imported
+os.environ['MPLBACKEND'] = 'GTK3Agg'   # or GTK3Cairo
+
+# 2) turn on every debug message GLib/GTK will give us
+os.environ['G_MESSAGES_DEBUG'] = 'all'
+os.environ['GTK_DEBUG'] = 'interactive'   # also enables Ctrl-Shift-I inspector
+
+import matplotlib
+matplotlib.use('GTK3Agg')          # belt-and-braces: make sure
+import matplotlib.pyplot as plt
+
+print('GTK3Agg backend loaded, creating figure…')
+fig, ax = plt.subplots()
+ax.plot([0, 1], [0, 1])
+ax.set_title('GTK3-Matplotlib window – close it to finish')
+print('Showing figure…')
+plt.show()
+print('plt.show() returned – script ends')
+