title: Remove border of tkinter button created with an image
body: <p>I've created a couple of buttons using my program and I've made them include images. However, I wish to now remove the border that remains (see <a href="https://i.imgur.com/XRlmq39.png" rel="noreferrer">http://i.imgur.com/XRlmq39.png</a> for screenshot).</p>
  
  <p>The code for the "back" button as an example:</p>
  
  <pre><code>backbutton = ttk.Button(mainframe, command=homereturn)
  backbuttonimage = PhotoImage(file="back.gif")
  backbutton.config(image=backbuttonimage)
  backbutton.pack()
  backbutton.grid(column=0, row=1)
  </code></pre>
  
  <p>Any help would be greatly appreciated.</p>