Tkinter, step 2: adapt imports.
diff --git a/Lib/idlelib/StackViewer.py b/Lib/idlelib/StackViewer.py
index 9ca1ff5..4ef2d31 100644
--- a/Lib/idlelib/StackViewer.py
+++ b/Lib/idlelib/StackViewer.py
@@ -7,7 +7,7 @@
 
 def StackBrowser(root, flist=None, tb=None, top=None):
     if top is None:
-        from Tkinter import Toplevel
+        from tkinter import Toplevel
         top = Toplevel(root)
     sc = ScrolledCanvas(top, bg="white", highlightthickness=0)
     sc.frame.pack(expand=1, fill="both")