title: How to get a menu checkbutton to call a function in Python + Tkinter?
body: <p>so, I'm now in a personal project (just to try myself) with python + tkinter. It is a encrypter, which means that it gets a piece of text and encrypts it using some famous cyphers (like the numerical cypher, the caesar's cypher, and others).<br>
  Now, I wanted to give the user the option to save the text he encrypted, and also the encrypted text generated by the program. For that, I created two checkbutton on the program's menu: one for "save text" and the other for "save encrypted text". My question is, I tried to attach a function as it's command option, so, I guess it should run that function when the option is clicked. But it isn't happening.<br>
  I'll just explain what the funcitions shouls do before passing the code.<br>
  They should prompt a question, asking the user if he/she really wants to create a text file with the text and the encrypted text (This isn't a database, it's just something for the user to be able to read later the text's he/she encrypted and the encrypted version, if he/she wants to).
  So, to the code:</p>
  
  <pre><code>encryptermenu = Menu(menubar, tearoff=0)
  encryptermenu.add_checkbutton(label="Save Text", variable=v, command=saveText)
  encryptermenu.add_checkbutton(label="Save Encrypted Text", variable=w, command=saveEncryptedText)
  menubar.add_cascade(label="Encrypter", menu=encryptermenu)
  </code></pre>
  
  <p>The checkbutton options, and now the functions:</p>
  
  <pre><code>def saveText():
      sdtst = messagebox.askyesno(title="Save Text", message="A .txt file will be created at the same directory as this program to save the text you decided to encrypt. Is it ok?")
  
  def saveEncryptedText():
      sdtset = messagebox.askyesno(title="Save Encrypted Text", message="A .txt file will be created at the same directory as this program to save the encrypted text generated by this program. Is it ok?")
  </code></pre>
  
  <p>Should the checkbutton really run the function on-click or am I just making confusion?
  Anyway, hope someone will help me.</p>