From 8a7a7a4394a02e32d6d0d4c005627c6664d507bc Mon Sep 17 00:00:00 2001
From: Serhiy Storchaka <storchaka@gmail.com>
Date: Wed, 1 Jul 2026 10:08:50 +0300
Subject: [PATCH] gh-82183: Do not restart the busy IDLE shell when running
 without restart

"Run... Customized" with "Restart shell" unchecked restarted the shell
anyway when it was busy executing code, killing any pending input.  It now
reports that the shell is executing and does not run.
---
 Lib/idlelib/idle_test/test_runscript.py       | 21 +++++++++++++++++++
 Lib/idlelib/runscript.py                      |  4 ++++
 ...6-07-01-19-00-00.gh-issue-82183.rNsTrt.rst |  3 +++
 3 files changed, 28 insertions(+)
 create mode 100644 Misc/NEWS.d/next/IDLE/2026-07-01-19-00-00.gh-issue-82183.rNsTrt.rst

diff --git a/Lib/idlelib/idle_test/test_runscript.py b/Lib/idlelib/idle_test/test_runscript.py
index 63086bfa4a404e9..1e47f402d504f9d 100644
--- a/Lib/idlelib/idle_test/test_runscript.py
+++ b/Lib/idlelib/idle_test/test_runscript.py
@@ -2,6 +2,7 @@
 
 from idlelib import runscript
 import unittest
+from unittest import mock
 from test.support import requires
 from tkinter import Tk
 from idlelib.editor import EditorWindow
@@ -28,6 +29,26 @@ def test_init(self):
         sb = runscript.ScriptBinding(ew)
         ew._close()
 
+    def test_run_module_event_shell_busy_no_restart(self):
+        # gh-82183: running without restarting the busy shell aborts.
+        ew = EditorWindow(root=self.root)
+        sb = runscript.ScriptBinding(ew)
+        sb.getfilename = mock.Mock(return_value='test.py')
+        sb.checksyntax = mock.Mock(return_value='code')
+        sb.tabnanny = mock.Mock(return_value=True)
+        sb.shell = shell = mock.Mock()
+        shell.executing = True
+        interp = shell.interp
+        with mock.patch.object(runscript, 'CustomRun') as customrun:
+            # Restart shell unchecked.
+            customrun.return_value.result = (['arg'], False)
+            result = sb.run_module_event(None, customize=True)
+        self.assertEqual(result, 'break')
+        interp.display_executing_dialog.assert_called_once()
+        interp.restart_subprocess.assert_not_called()
+        interp.runcode.assert_not_called()
+        ew._close()
+
 
 if __name__ == '__main__':
     unittest.main(verbosity=2)
diff --git a/Lib/idlelib/runscript.py b/Lib/idlelib/runscript.py
index 55712e904603f86..cd52d206c9ca0f3 100644
--- a/Lib/idlelib/runscript.py
+++ b/Lib/idlelib/runscript.py
@@ -139,6 +139,10 @@ def run_module_event(self, event, *, customize=False):
                 return 'break'
         self.cli_args, restart = run_args if customize else ([], True)
         interp = self.shell.interp
+        if self.shell.executing and not restart:
+            # Cannot run without restarting the busy shell (gh-82183).
+            interp.display_executing_dialog()
+            return 'break'
         if pyshell.use_subprocess and restart:
             interp.restart_subprocess(
                     with_cwd=False, filename=filename)
diff --git a/Misc/NEWS.d/next/IDLE/2026-07-01-19-00-00.gh-issue-82183.rNsTrt.rst b/Misc/NEWS.d/next/IDLE/2026-07-01-19-00-00.gh-issue-82183.rNsTrt.rst
new file mode 100644
index 000000000000000..2af412f5200d0de
--- /dev/null
+++ b/Misc/NEWS.d/next/IDLE/2026-07-01-19-00-00.gh-issue-82183.rNsTrt.rst
@@ -0,0 +1,3 @@
+When the shell is busy running code, using "Run... Customized" with "Restart
+shell" unchecked now reports that the shell is executing instead of
+restarting it anyway.