title: Python GUI both compatible GTK2 and GTK3
body: <p>I'd like to create a graphical interface in python2 with GTK+.</p>
  
  <p>For now I'm using gobject-introspection to use GTK3 but I'd like, if possible, to be compatible with GTK2 as well.</p>
  
  <pre><code>#!/usr/bin/python2
  try:
      from gi.repository import Gtk
  except:
      try:
          import gtk as Gtk
      except:
          print("You need GTK")
  </code></pre>
  
  <p>I was using a Grid for my window but it seems <code>Gtk.Grid</code> doesn't exist in GTK2. On the other hand <code>Gtk.Table</code> exists in both version.</p>
  
  <p>Is it worth the try to make an app compatible for both version of GTK (and how ?) or I'll have to write almost twice more code ?</p>
  
  <p>Thanks</p>