Library: Port 'Spell Checker' to Python (#758)

Author: UrtsiSantsi

src/Library/demos/Spell Checker/main.py

@@ -0,0 +1,22 @@
+import gi
+
+gi.require_version("Gtk", "4.0")
+gi.require_version("GtkSource", "5")
+from gi.repository import Gtk, GtkSource, Spelling
+import workbench
+
+GtkSource.init()
+
+buffer: GtkSource.Buffer = workbench.builder.get_object("buffer")
+text_view: Gtk.TextView = workbench.builder.get_object("text_view")
+
+# Spell checking setup
+checker = Spelling.Checker.get_default()
+checker.set_language("en_US")  # set to U.S English
+adapter = Spelling.TextBufferAdapter.new(buffer, checker)
+extra_menu = adapter.get_menu_model()
+
+text_view.set_extra_menu(extra_menu)
+text_view.insert_action_group("spelling", adapter)
+
+adapter.set_enabled(True)