title: ListBox with CheckButtons in python with Tkinter
body: <p>here is a code to define a scrollbar in a listbox with Tkinter :</p>
  
  <pre><code>import tkinter as tk
  
  root = tk.Tk()
  
  scrollbar = tk.Scrollbar(root)
  scrollbar.pack(side=tk.RIGHT, fill=tk.Y)
  
  listbox = tk.Listbox(root)
  listbox.pack()
  
  for i in range(50):
    listbox.insert(tk.END, i)
  
  listbox.config(yscrollcommand=scrollbar.set)
  scrollbar.config(command=s.set)
  
  root.mainloop()
  </code></pre>
  
  <p>I want to adapt this code to have a scrollbar with checkbuttons, I know I can't fill a Listbox with Checkbuttons because listbox can only contain text        </p>
  
  <pre><code>scrollbar = tk.Scrollbar(self)
  scrollbar.pack(side=tk.RIGHT, fill=tk.Y)
  categories = ["aaa","bbb","ccc"]
  for i in categories:
      var[i] = tk.IntVar()
      chk = tk.Checkbutton(self, text=i, variable=var[i], width=20)
      #chk.select()
      chk.pack()
  
  scrollbar.config(command=s.set)
  </code></pre>
  
  <p>How can I make my Checkbuttons "scrollable" ? </p>