title: ComboBox not present in TK
body: <p>According to the docs there should be a <code>ComboBox</code> operation in TK, but I can't find it. <code>dir(tk)</code> shows</p>
  
  <blockquote>
    <p>['ACTIVE', 'ALL', 'ANCHOR', 'ARC', 'At', 'AtEnd', 'AtInsert', 'AtSelFirst', 'AtSelLast', 'BASELINE', 'BEVEL', 'BOTH', 'BOTTOM', 'BROWSE', 'BUTT', 'BaseWidget', 'BitmapImage', 'BooleanType', 'BooleanVar', 'BufferType', 'BuiltinFunctionType', 'BuiltinMethodType', 'Button', 'CASCADE', 'CENTER', 'CHAR', 'CHECKBUTTON', 'CHORD', 'COMMAND', 'CURRENT', 'CallWrapper', 'Canvas', 'Checkbutton', 'ClassType', 'CodeType', 'ComplexType', 'DISABLED', ...</p>
  </blockquote>
  
  <p>The version is</p>
  
  <pre><code>import Tkinter as tk
  tk.__version__
  </code></pre>
  
  <blockquote>
    <p>'$Revision: 81008 $'</p>
  </blockquote>
  
  <p>on my Mac (latest OS X 10.11.6). No brewery for python whatsoever. </p>