title: Python 3 Error: "NameError: global name 'entryWidget' is not defined"
body: <p>I get the error "NameError: global name 'entryWidget' is not defined" in the following piece of Python 3 tkinter code:</p>
  
  <pre><code>from tkinter import *
  import tkinter
  
  def displayText():
      tkinter.messagebox.showinfo("Tkinter Entry Widget", "Text value =" + entryWidget)
  
  class Application(Frame):
  
      def createWidgets(self):
  
          root.title("TITLE")
  
          textFrame = Frame(root)
          entryLabel = Label(textFrame)
          entryLabel["text"] = "Enter the text:"
          entryLabel.pack(side=LEFT)
  
          entryWidget = Entry(textFrame)
          entryWidget["width"] = 50
          entryWidget.pack(side=LEFT)
          textFrame.pack()
          button = Button(root, text="Submit", command=displayText)
          button.pack()
  
          self.QUIT = Button(self)
          self.QUIT["text"] = "QUIT"
          self.QUIT["fg"] = "red"
          self.QUIT["command"] = self.quit
          self.QUIT.pack()
  
  
      def __init__(self, master=None):
          Frame.__init__(self, master)
          self.pack()
          self.createWidgets()
  
  root = Tk()
  app = Application(master=root)
  app.mainloop()
  root.destroy()
  </code></pre>
  
  <p>The code itself is designed to create a text box (with text next to it), an enter button for the text box and a quit button. When text is entered in the text box and enter is pressed then a message box should appear telling the user what they entered. The quit button just quits the script.</p>
  
  <p>How can I fix the error I am getting (I am aware what the error means, just don't know how to fix it in this scenario). Note that I am new to tkinter and GUI code.</p>