title: Submenu item does not call function [with working solution]
body: <pre><code>    #submenu
      clearMenu = gtk.Menu()
  
      item = gtk.MenuItem("submenu item")
      item.connect("activate", lambda w: self.callBackFunction())
      clearMenu.append(item)
      item.show()
  
  
      '''TOP level'''
      menu = gtk.Menu()
  
      item = gtk.ImageMenuItem("Item1")
      img = gtk.Image()
      img.set_from_file('image1.png')
      item.set_image(img)
      menu.append(item)
      item.set_submenu(clearMenu) #attach submenu
      item.show()
  
      item = gtk.ImageMenuItem("Item2")
      img = gtk.Image()
      img.set_from_file('image2.png')
      item.set_image(img)   
      item.connect("activate", lambda w: self.callBackFunction())
      menu.append(item)
      item.show()
  </code></pre>
  
  <p>My top level item "Item2" calls defined function "callBackFunction". But why "submenu item" <strong>does not</strong>?
  What i'm doing wrong?</p>
  
  <hr>
  
  <p>EDIT</p>
  
  <p>here is how i've managed to force <strong>submenu items</strong> kick-in desired action:</p>
  
  <pre><code>item.connect("button-press-event", self.callBackFunction, argument1, argument2)
  </code></pre>
  
  <p>But i still dont get it why event "activate" does not works on submenu items, while works in top level menu items</p>