title: Make edges of button disappear in tkinter
body: <p>I have a customized button, on which I loaded an icon like this:
  <a href="https://i.stack.imgur.com/WcJpt.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/WcJpt.png" alt="enter image description here"></a></p>
  
  <p>but as you can see there's a "box" around the button. The icon itself doesn't have background, so I guess the box is added by tkinter to indicate that this is a button. Is there a way to make those four lines disappear?</p>
  
  <p>Thanks in advance. </p>