title: Tkinter Treeview cannot edit more that one column
body: <p>I use a Tkinter TreeView that I populate with data from a file.</p>
  
  <p>The result is 6 columns of prefilled numeric data for each row.
  Some rows has a single column value, others has multiple columns filled with data, editable by the user (upon mouse right click).</p>
  
  <p>For rows with single editable column, I use the following piece of code:</p>
  
  <pre><code>...
  self.tree.insert(id2 , 2,    text=key2.strip('\r\n'), \
    values=("","","10","","",""), \
    tags=('','','tag3','','',''))
    self.tree.tag_bind(('','','tag3','','',''), '&lt;Button-3&gt;', self.popupEntry)
  ...
  </code></pre>
  
  <p><strong>Result: (OK)</strong>
  If right click then dialogbox popup with text entry, upon validation, the column of he corresponding row is <strong>successfully</strong> filled with the new value. This works for any single value tuple "tags".</p>
  
  <p>But, for rows with more that one editable column I modified the previous code as follow:</p>
  
  <pre><code>...
  self.tree.insert(id2 , 2,    text=key2.strip('\r\n'), \
    values=("","","10","","","10"), \
    tags=('','','tag3','','','tag6'))
    self.tree.tag_bind(('','','tag3','','','tag6'), '&lt;Button-3&gt;', self.popupEntry)
  ...
  </code></pre>
  
  <p><strong>Result: (Not OK)</strong>
  No reaction to mouse Right click, nothing happens</p>
  
  <p><strong>Desired behavior:</strong>
  - for rows with 2 or more editable columns, right-click to spawn dialogbox with 2 text entries, upon validation, the 2 column values are filled. </p>
  
  <p>Something like that:
  <img src="https://i.stack.imgur.com/vTAdw.png" alt="enter image description here"></p>
  
  <p><strong>Popup code:</strong></p>
  
  <pre><code>   def popupEntry(self, event):
          result = tkSimpleDialog.askinteger("New value", "Please enter a new numeric value")
          if result:
              self.tree.item(self.tree.focus(), values=self.tag_to_val(self.tree.item(self.tree.focus(), 'tags'), result))
  </code></pre>