title: Changing TkInter Scale won't update label "bg"
body: <p>Here is my code:</p>
  
  <pre><code>slowColor = (255,0,255)
  
  window = Tk()
  window.title = 'Mouse Tracker'
  
  label1 = Label(window, text='Slow Color')
  label1.grid(row=1, column=3, columnspan=5)
  label2 = Label(window, bg='#%02x%02x%02x' % slowColor)
  label2.grid(row=2, column=1, rowspan=2, columnspan=9, sticky=NW+SE)
  label3 = Label(window, text='R')
  label3.grid(row=4, column=2)
  label4 = Label(window, text='G')
  label4.grid(row=4, column=5)
  label5 = Label(window, text='B')
  label5.grid(row=4, column=8)
  slider1 = Scale(window, from_=255, to=0)
  slider1.grid(row=5, column=2, rowspan=6)
  slider2 = Scale(window, from_=255, to=0)
  slider2.grid(row=5, column=5, rowspan=6)
  slider3 = Scale(window, from_=255, to=0)
  slider3.grid(row=5, column=8, rowspan=6)
  label2.config(bg='#%02x%02x%02x' % (slider1.get(), slider2.get(), slider3.get()))
  </code></pre>
  
  <p>What's supposed to happen is that changing the value of one of the sliders, should change the "bg" color of label2.  But that isn't happening.  Label2 remains static.</p>