From b0f15d30a4b01bec2304de30858361554750917b Mon Sep 17 00:00:00 2001
From: E-Paine <63801254+E-Paine@users.noreply.github.com>
Date: Sat, 11 Sep 2021 15:41:39 +0100
Subject: [PATCH 1/3] Ttk optionmenu not use _setit

---
 Lib/tkinter/ttk.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/Lib/tkinter/ttk.py b/Lib/tkinter/ttk.py
index b854235a6267935..acdd565ec48a92c 100644
--- a/Lib/tkinter/ttk.py
+++ b/Lib/tkinter/ttk.py
@@ -1643,7 +1643,10 @@ def set_menu(self, default=None, *values):
         menu.delete(0, 'end')
         for val in values:
             menu.add_radiobutton(label=val,
-                command=tkinter._setit(self._variable, val, self._callback),
+                command=(
+                    None if self._callback is None
+                    else lambda val=val: self._callback(val)
+                ),
                 variable=self._variable)
 
         if default:

From 826c4fd74ae4599bb6aa53f5b8e5be51f23cb33a Mon Sep 17 00:00:00 2001
From: "blurb-it[bot]" <43283697+blurb-it[bot]@users.noreply.github.com>
Date: Sat, 11 Sep 2021 14:47:06 +0000
Subject: [PATCH 2/3] =?UTF-8?q?=F0=9F=93=9C=F0=9F=A4=96=20Added=20by=20blu?=
 =?UTF-8?q?rb=5Fit.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../NEWS.d/next/Library/2021-09-11-14-47-05.bpo-45160.VzMXbW.rst | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Misc/NEWS.d/next/Library/2021-09-11-14-47-05.bpo-45160.VzMXbW.rst

diff --git a/Misc/NEWS.d/next/Library/2021-09-11-14-47-05.bpo-45160.VzMXbW.rst b/Misc/NEWS.d/next/Library/2021-09-11-14-47-05.bpo-45160.VzMXbW.rst
new file mode 100644
index 000000000000000..9d11ed0e55d24cf
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-09-11-14-47-05.bpo-45160.VzMXbW.rst
@@ -0,0 +1 @@
+When tracing a tkinter variable used by a ttk OptionMenu, callbacks are no longer made twice.
\ No newline at end of file

From 13545094d4352bd2f7b8b7a2a181179c8ef41248 Mon Sep 17 00:00:00 2001
From: E-Paine <63801254+E-Paine@users.noreply.github.com>
Date: Fri, 17 Sep 2021 17:31:03 +0100
Subject: [PATCH 3/3] Add test

---
 Lib/tkinter/test/test_ttk/test_extensions.py | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/Lib/tkinter/test/test_ttk/test_extensions.py b/Lib/tkinter/test/test_ttk/test_extensions.py
index e6b3eccf7afb8a0..4da3845e01301e6 100644
--- a/Lib/tkinter/test/test_ttk/test_extensions.py
+++ b/Lib/tkinter/test/test_ttk/test_extensions.py
@@ -301,6 +301,19 @@ def test_unique_radiobuttons(self):
         optmenu.destroy()
         optmenu2.destroy()
 
+    def test_trace_variable(self):
+        # prior to bpo45160, tracing a variable would cause the callback to be made twice
+        success = []
+        items = ('a', 'b', 'c')
+        textvar = tkinter.StringVar(self.root)
+        def cb_test(*args):
+            self.assertEqual(textvar.get(), items[1])
+            success.append(True)
+        optmenu = ttk.OptionMenu(self.root, textvar, "a", *items)
+        textvar.trace("w", cb_test)
+        optmenu['menu'].invoke(1)
+        self.assertEqual(success, [True])
+
 
 class DefaultRootTest(AbstractDefaultRootTest, unittest.TestCase):