gh-103820: IDLE: Do not interpret buttons 4/5 as scrolling on non-X11 (GH-103821)

Also fix test_mousewheel: do not skip a check which was broken due to incorrect
delta on Aqua and XQuartz, and probably not because of `.update_idletasks()`.

1 files changed, 14 insertions, 8 deletions

diff --git a/Lib/idlelib/idle_test/test_sidebar.py b/Lib/idlelib/idle_test/test_sidebar.py
index fb52b3a..605e7a8 100644
--- a/Lib/idlelib/idle_test/test_sidebar.py
+++ b/Lib/idlelib/idle_test/test_sidebar.py
@@ -690,16 +690,22 @@ class ShellSidebarTest(unittest.TestCase):
         last_lineno = get_end_linenumber(text)
         self.assertIsNotNone(text.dlineinfo(text.index(f'{last_lineno}.0')))
 
-        # Scroll up using the <MouseWheel> event.
-        # The meaning of delta is platform-dependent.
-        delta = -1 if sys.platform == 'darwin' else 120
-        sidebar.canvas.event_generate('<MouseWheel>', x=0, y=0, delta=delta)
+        # Delta for <MouseWheel>, whose meaning is platform-dependent.
+        delta = 1 if sidebar.canvas._windowingsystem == 'aqua' else 120
+
+        # Scroll up.
+        if sidebar.canvas._windowingsystem == 'x11':
+            sidebar.canvas.event_generate('<Button-4>', x=0, y=0)
+        else:
+            sidebar.canvas.event_generate('<MouseWheel>', x=0, y=0, delta=delta)
         yield
-        if sys.platform != 'darwin':  # .update_idletasks() does not work.
-            self.assertIsNone(text.dlineinfo(text.index(f'{last_lineno}.0')))
+        self.assertIsNone(text.dlineinfo(text.index(f'{last_lineno}.0')))
 
-        # Scroll back down using the <Button-5> event.
-        sidebar.canvas.event_generate('<Button-5>', x=0, y=0)
+        # Scroll back down.
+        if sidebar.canvas._windowingsystem == 'x11':
+            sidebar.canvas.event_generate('<Button-5>', x=0, y=0)
+        else:
+            sidebar.canvas.event_generate('<MouseWheel>', x=0, y=0, delta=-delta)
         yield
         self.assertIsNotNone(text.dlineinfo(text.index(f'{last_lineno}.0')))