From 152d306158a33f80bb16db2adf27f83dc31b4c72 Mon Sep 17 00:00:00 2001
From: Zackery Spytz <zspytz@gmail.com>
Date: Thu, 14 Nov 2019 23:41:43 -0700
Subject: [PATCH] bpo-23544: IDLE hangs when selecting Stack Viewer with debug
 active

"Stack Viewer" is now disabled when user code is running.
---
 Lib/idlelib/editor.py                                         | 4 +++-
 Lib/idlelib/pyshell.py                                        | 4 ++++
 .../NEWS.d/next/IDLE/2019-11-14-23-41-07.bpo-23544.3etemb.rst | 2 ++
 3 files changed, 9 insertions(+), 1 deletion(-)
 create mode 100644 Misc/NEWS.d/next/IDLE/2019-11-14-23-41-07.bpo-23544.3etemb.rst

diff --git a/Lib/idlelib/editor.py b/Lib/idlelib/editor.py
index dff104ff0f1..cba34bf8f6b 100644
--- a/Lib/idlelib/editor.py
+++ b/Lib/idlelib/editor.py
@@ -449,7 +449,9 @@ class EditorWindow(object):
         self.menudict = menudict = {}
         for name, label in self.menu_specs:
             underline, label = prepstr(label)
-            menudict[name] = menu = Menu(mbar, name=name, tearoff=0)
+            postcommand = getattr(self, f'{name}_menu_postcommand', None)
+            menudict[name] = menu = Menu(mbar, name=name, tearoff=0,
+                                         postcommand=postcommand)
             mbar.add_cascade(label=label, menu=menu, underline=underline)
         if macosx.isCarbonTk():
             # Insert the application menu
diff --git a/Lib/idlelib/pyshell.py b/Lib/idlelib/pyshell.py
index 065122dec7a..d8d67e7d9bf 100755
--- a/Lib/idlelib/pyshell.py
+++ b/Lib/idlelib/pyshell.py
@@ -990,6 +990,10 @@ class PyShell(OutputWindow):
         self.showprompt()
         self.set_debugger_indicator()
 
+    def debug_menu_postcommand(self):
+        state = 'disabled' if self.executing else 'normal'
+        self.update_menu_state('debug', '*Stack Viewer', state)
+
     def beginexecuting(self):
         "Helper for ModifiedInterpreter"
         self.resetoutput()
diff --git a/Misc/NEWS.d/next/IDLE/2019-11-14-23-41-07.bpo-23544.3etemb.rst b/Misc/NEWS.d/next/IDLE/2019-11-14-23-41-07.bpo-23544.3etemb.rst
new file mode 100644
index 00000000000..aa6b504a793
--- /dev/null
+++ b/Misc/NEWS.d/next/IDLE/2019-11-14-23-41-07.bpo-23544.3etemb.rst
@@ -0,0 +1,2 @@
+The "Stack Viewer" item in the "Debug" menu can no longer be selected when
+user code is running.