title: tkinter rendering wrong RGB shade in python
body: <p>I am using tkinter in Python (3.5.1). The problem is that actual RGB values are not corresponding to the RGB in tkinter.</p>
  
  <p>For example in this code:</p>
  
  <pre><code>import tkinter
  root=tkinter.Tk()
  root.configure(bg="white")
  root.mainloop()
  </code></pre>
  
  <p>It works as expected. However if I replace "white" with "#255255255" the background is grey. And same happens with other widgets too.</p>
  
  <p>So I read the color manual docs on tkinter site, and as per the table this RGB corresponded to "grey100".
  Why is it different?
  I need the actual correspondence of RGB. Am I doing something wrong, or do I needs external calibration to achieve so ?</p>