title: Python Tkinter: Passing arguments to Button widget
body: <p>I have some confusion about the way a function "processOK" is being called here. it usually is something like command=processOK(). I ve recently started learning Python as an additional skill, would be thankful if you could clarify. Also please state the difference between a normal class and widget classes.</p>
  
  <pre><code>btOK = Button(window, text = "OK", fg = "red", command = processOK)
  </code></pre>