title: How to use Combobox with dictionnary
body: <p>I try to reproduce a list as we can do in html</p>
  <pre><code>&lt;select id=&quot;monselect&quot;&gt;
    &lt;option value=&quot;valeur1&quot;&gt;Valeur 1&lt;/option&gt; 
    &lt;option value=&quot;valeur2&quot; selected&gt;Valeur 2&lt;/option&gt;
    &lt;option value=&quot;valeur3&quot;&gt;Valeur 3&lt;/option&gt;
  &lt;/select&gt;
  </code></pre>
  <p>in python 3, I should have something like that :</p>
  <pre><code>mydict = {´value1':'abc', 'value2':'qwe'}
  
  combobox = ttk.Combobox(self.frame, values=list(mydict.values()), textvariable=selected, width=70)
  combobox.grid(row=0, column=2, sticky=NSEW)
  </code></pre>
  <p>it will print a box with 'abc' and 'qwe'
  How can i only keep the value 'value1´ or 'value2' store in the combobox ?</p>