UI: Add test for preferences section drawing

The test opens the Preferences window, switches through every value of
``preferences.active_section``, expands dynamic sections like Add-ons,
and yields  after each change so the UI can redraw.

This lets us find UI errors in the many navigation sections of the
Preferences.

Pull Request: https://projects.blender.org/blender/blender/pulls/161693

---------

Co-authored-by: Pratik Borhade <25420+pratikpb2123@noreply.localhost>

tests/python/ui_simulate/test_preferences_draw_all.py

@@ -0,0 +1,67 @@
+# SPDX-FileCopyrightText: 2026 Blender Authors
+#
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+"""
+This file does not run anything, its methods are accessed for tests by ``run_blender_setup.py``.
+"""
+
+import modules.ui_test_utils as ui
+
+
+def _find_preferences_window():
+    """Find the Preferences window if it exists."""
+    import bpy
+
+    for window in bpy.context.window_manager.windows:
+        for area in window.screen.areas:
+            if area.type == "PREFERENCES":
+                return window, area
+
+    return None, None
+
+
+def test_preferences_draw_all():
+    """Test that all Preferences sections draw correctly."""
+    import bpy
+    import addon_utils
+
+    _, t, window = ui.test_window()
+
+    # Open Preferences window.
+    with bpy.context.temp_override(window=window):
+        bpy.ops.screen.userpref_show()
+
+    yield
+
+    prefs_window, prefs_area = _find_preferences_window()
+
+    t.assertIsNotNone(prefs_window, "Preferences window was not opened")
+    t.assertIsNotNone(prefs_area, "Preferences area was not found")
+
+    prefs = bpy.context.preferences
+    original_save = prefs.use_preferences_save
+    original_show_addons_enabled_only = prefs.view.show_addons_enabled_only
+    prefs.use_preferences_save = False
+    prefs.view.show_addons_enabled_only = False
+
+    def expand_addons():
+        for mod in addon_utils.modules(refresh=False):
+            bl_info = addon_utils.module_bl_info(mod)
+            if bl_info["show_expanded"]:
+                continue
+
+            with bpy.context.temp_override(window=prefs_window, area=prefs_area):
+                bpy.ops.preferences.addon_expand(module=mod.__name__)
+            yield
+
+    try:
+        for item in prefs.bl_rna.properties["active_section"].enum_items:
+            with bpy.context.temp_override(window=prefs_window, area=prefs_area):
+                prefs.active_section = item.identifier
+            yield
+            if item.identifier == "ADDONS":
+                yield from expand_addons()
+    finally:
+        prefs.use_preferences_save = original_save
+        prefs.view.show_addons_enabled_only = original_show_addons_enabled_only