title: How to make default text in entry that disappears
body: <p>For instance:</p>
  
  <pre><code>from Tkinter import *
  root = Tk()
  
  e1 = Entry(root)
  e1.insert(END, "ex. new file")  #would like to make this text disappear when clicked
  e1.grid(row=0, column=0)
  
  root.mainloop()
  </code></pre>
  
  <p>Where the text "ex. newfile" disappears when clicked upon, leaving a blank entry field.</p>