title: Python tkinter Treeview more columns than specified
body: <p>I have the following code for a ttk Treeview:</p>
  <pre><code>listbox = ttk.Treeview(
      tab_player,
      columns=('Player', 'Rating', 'Price'),
      selectmode=&quot;extended&quot;,
  )
  
  listbox.heading('#0', text='Player', anchor=tk.CENTER)
  listbox.heading('#1', text='Rating', anchor=tk.CENTER)
  listbox.heading('#2', text='Price', anchor=tk.CENTER)
  listbox.column('#0', stretch=tk.YES, minwidth=50, width=80)
  listbox.column('#1', stretch=tk.YES, minwidth=50, width=20)
  listbox.column('#2', stretch=tk.YES, minwidth=50, width=30)
  
  listbox.grid(row=5, column=5, rowspan=7, sticky=W)
  </code></pre>
  <p>My insert function is as follows:</p>
  <pre><code>def insertitem():
          GUI.listbox.insert('', 'end', values = (GUI.listbox_content.get(), 
                                                  GUI.listboxr_content.get(), 
                                                  GUI.listbox_content_price.get()))
  </code></pre>
  <p>When I launch my app, I have one additional column and the inserted data is not as I want (data in wrong columns).</p>
  <p><a href="https://i.stack.imgur.com/Uy7xb.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Uy7xb.png" alt="enter image description here" /></a></p>
  <p>Why is that?</p>