title: If statement based on listbox with PySimpleGui
body: <p>So i have been having some issues with a if statement based on the PySimpleGui listbox element.
  The code i have is:</p>
  <pre class="lang-py prettyprint-override"><code>layout = [[sg.Listbox(values=['Listbox 1', 'Listbox 2', 'Listbox 3'], size=(30, 6))],
            [sg.Button('Next'), sg.Button('Quit')]]
  
  window = sg.Window('PyK Mn', layout)
  
  #############
  # MAIN LOOP #
  #############
  while True:
      event, values = window.read()
      print(event)
      if event == sg.WIN_CLOSED or event == 'Quit':
          quit()
      elif event == 'Next':
          if values[0] == 'Listbox 3':
              print('3')
  </code></pre>
  <p>When i run this it returns 'Next' but no '3'. What am i doing wrong?</p>