title: Button doesn't show up tkinter
body: <p>I have a class that represents a Window that contains a canvas, a label and is soon to contain some color-coordinated buttons.</p>
  <p><em><strong>Here is the code:</strong></em></p>
  <pre class="lang-py prettyprint-override"><code>class Canvas():
      def __init__(self, width, height):
          self.root = tk.Tk()
          self.width = width
          self.height = height
  
  
          self.text_label = tk.Label(self.root, text=&quot;10&quot;,font=(&quot;Times New Roman&quot;, 20, &quot;italic&quot;))
          self.text_label.pack()
  
          self.canvas = tk.Canvas(master= self.root,width = self.width,height = self.height)
          self.canvas.pack()
  
          
  
          #======================
          self.redBtn = tk.Button(master=self.root,text=&quot;hello&quot;,command=lambda:self.changeColor(&quot;Red&quot;))
          self.redBtn.pack()
          #======================
  
          self.root.mainloop()
  canvas = Canvas(1980,1080)
  </code></pre>
  <p>Although I used <code>redBtn.pack()</code> on the button it doesn't show up.
  Does anyone know why?</p>
  <p><a href="https://i.stack.imgur.com/dkQME.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/dkQME.png" alt="The window:" /></a></p>