title: Beginner-Question: Python Tkinter Frames hiding behind small label
body: <p>I have a beginner question about python tkinter:</p>
  <p>I've got a Frame like this:</p>
  <pre><code>import tkinter
  
  root = tkinter.Tk()
  root.geometry('100x100')
  
  frame = tkinter.Frame(root, width=100, height=80, bg='green')
  frame.pack()
  
  root.mainloop()
  </code></pre>
  <p>The result is a window, thats mostly green. Now i want to place a Label on that green area. Thus I add the following between <em>frame.pack()</em> and <em>root.mainloop()</em>:</p>
  <pre><code>label = tkinter.Label(frame, text='TESTTEST')
  label.pack()
  </code></pre>
  <p>This results in a window printing <em>TESTTEST</em>. But nothing is green anymore. Where did my Frame go? The text isn't close to being big enough to completely cover the green area with it's own background.</p>
  <p>What am I doing wrong? Why doesn't it work like that?</p>
  <p>Putting another Frame between <em>frame</em> and <em>label</em> like this:</p>
  <pre><code>frame2 = tkinter.Frame(frame, width=100, height=20)
  frame2.pack()
  </code></pre>
  <p>results in an area above the Label being colourless. However, to the left and right of my Label it's green?!
  Neither above nor below is any green. Just left and right of my Label.</p>
  <p>How does this work?</p>