fixing warnings and deprecated calls

[WhiteSymmetry]

Requirements.txt for Ubuntu 25.10.

mesa-utils for "import gi"

fixing warnings and deprecated calls:

test.py:24: PyGIWarning: Gtk was imported without specifying a version first. Use gi.require_version('Gtk', '3.0') before import to ensure that the right version gets loaded.
from gi.repository import Gtk
test.py:47: DeprecationWarning: Gtk.ScrolledWindow.add_with_viewport is deprecated
sw.add_with_viewport(canvas)

Primary Change: Version Specification

• Old Code: Imported Gtk directly without specifying which version to use. This triggered a warning because the binding is not future-proof.
• New Code: Explicitly specifies gi.require_version('Gtk', '3.0') before the import. This ensures the correct API version is loaded and eliminates the warning.

Structural & Maintenance Improvements

• Old Code: Used a simple procedural script. The UI was built directly in the global scope.
• New Code: Encapsulates the application logic within a MatplotlibGTKWindow class. This is a better practice for organization, reusability, and managing the state of the application.

UI/UX Refinements

• Old Code: Used the deprecated add_with_viewport method to add the widget to the Gtk.ScrolledWindow.
• New Code: Uses the modern and correct add method for Gtk.ScrolledWindow.
• New Code: Explicitly sets the scrollbar policy to Gtk.PolicyType.AUTOMATIC, making the scrollbars appear only when needed.
• New Code: Enhances the plot with labels, a title, a grid, and a specific line style for better readability and a more complete example.

In summary, the update focuses on correctness (fixing warnings and deprecated calls), modern structure (using a class), and improved user experience (better plot and scrollbar behavior).