Issue #27922: IDLE test_idlehistory no longer flash tk widgets.
(Omitted for 2.7 from previous patch.)
diff --git a/Lib/idlelib/idle_test/test_idlehistory.py b/Lib/idlelib/idle_test/test_idlehistory.py
index dc6bb32..b076757 100644
--- a/Lib/idlelib/idle_test/test_idlehistory.py
+++ b/Lib/idlelib/idle_test/test_idlehistory.py
@@ -68,6 +68,7 @@
     def setUpClass(cls):
         requires('gui')
         cls.root = tk.Tk()
+        cls.root.withdraw()
 
     def setUp(self):
         self.text = text = TextWrapper(self.root)