diff -r ab28676df655 Lib/tkinter/tix.py
--- a/Lib/tkinter/tix.py	Mon Jul 25 02:21:14 2016 +0000
+++ b/Lib/tkinter/tix.py	Mon Jul 25 06:00:56 2016 +0300
@@ -26,8 +26,10 @@
 # appreciate the advantages.
 #
 
+import os
+import tkinter
 from tkinter import *
-from tkinter import _cnfmerge, _default_root
+from tkinter import _cnfmerge
 
 import _tkinter # If this fails your Python may not be configured for Tk
 
@@ -68,7 +70,6 @@ TCL_ALL_EVENTS    = 0
 # BEWARE - this is implemented by copying some code from the Widget class
 #          in Tkinter (to override Widget initialization) and is therefore
 #          liable to break.
-import tkinter, os
 
 # Could probably add this to Tkinter.Misc
 class tixCommand:
@@ -471,11 +472,16 @@ class DisplayStyle:
     """DisplayStyle - handle configuration options shared by
     (multiple) Display Items"""
 
-    def __init__(self, itemtype, cnf={}, **kw):
-        master = _default_root              # global from Tkinter
-        if not master and 'refwindow' in cnf: master=cnf['refwindow']
-        elif not master and 'refwindow' in kw:  master= kw['refwindow']
-        elif not master: raise RuntimeError("Too early to create display style: no root window")
+    def __init__(self, itemtype, cnf={}, *, master=None, **kw):
+        if not master:
+            if 'refwindow' in cnf:
+                master = cnf['refwindow']
+            elif 'refwindow' in kw:
+                master = kw['refwindow']
+            else:
+                master = tkinter._default_root
+                if not master:
+                    raise RuntimeError("Too early to create display style: no root window")
         self.tk = master.tk
         self.stylename = self.tk.call('tixDisplayStyle', itemtype,
                             *self._options(cnf,kw) )