old_contents: import wx
  import wx.html
  
  
  class LessonsWindow(wx.Frame):
      def __init__(self):
          wx.Frame.__init__(self, None, title="Instructions", size=(640, 1024))
          subbox = wx.BoxSizer(wx.HORIZONTAL)
  
          button_prev = wx.Button(self, -1, 'Prev')
          self.Bind(wx.EVT_BUTTON, self.OnPrev, button_prev)
          subbox.Add(button_prev, 1, wx.GROW | wx.ALL, 2)
  
          button_play_pause = wx.Button(self, -1, 'Run/Puase')
          self.Bind(wx.EVT_BUTTON, self.OnRunPause, button_play_pause)
          subbox.Add(button_play_pause, 1, wx.GROW | wx.ALL, 2)
  
          button_next = wx.Button(self, -1, 'Next')
          self.Bind(wx.EVT_BUTTON, self.OnNext, button_next)
          subbox.Add(button_next, 1, wx.GROW | wx.ALL, 2)
  
          self.html_window = wx.html.HtmlWindow(self)
          contents = """\
  <!DOCTYPE html>
  <html>
  <head>
      <title>Welcome to Orbital Academy</title>
  </head>
  <body>
      <h3><center>Welcome to <b>Orbital Academy</b></center></h3>
      <p>Orbital Academy is a place to learn orbital mechanics. The curriculum is organized into lessons
      of progressive difficulty. After you completed them all you will have become an expert spacecraft pilot!</p>
      <br>
      <p>The display on the left shows Earth orbital space.</p>
      <p>You can rotate the view by dragging with the right mouse button, and zoom in and out using the mouse wheel.</p>
      <br>
      <p>Click on a lesson to start your journey!</p>
  </body>
  </html>
  """
          self.html_window.SetPage(contents)
  
          sizer = wx.BoxSizer(wx.VERTICAL)
          sizer.Add(self.html_window, 1, wx.EXPAND)
          sizer.Add(subbox, 0, wx.EXPAND)
  
          self.SetSizer(sizer)
  
          self.Bind(wx.EVT_CLOSE, self.OnClose)
  
      def OnPrev(self, evt):
          print 'OnPrev'
  
      def OnNext(self, evt):
          print 'OnNext'
  
      def OnRunPause(self, evt):
          print 'OnRunPause'
  
      def OnClose(self, evt):
          self.Destroy()
  
new_contents: import wx
  import wx.html
  
  
  class LessonsWindow(wx.Frame):
      def __init__(self):
          wx.Frame.__init__(self, None, title="Instructions", size=(640, 1024))
          subbox = wx.BoxSizer(wx.HORIZONTAL)
  
          button_prev = wx.Button(self, -1, 'Prev')
          self.Bind(wx.EVT_BUTTON, self.OnPrev, button_prev)
          subbox.Add(button_prev, 1, wx.GROW | wx.ALL, 2)
  
          button_play_pause = wx.Button(self, -1, 'Run/Puase')
          self.Bind(wx.EVT_BUTTON, self.OnRunPause, button_play_pause)
          subbox.Add(button_play_pause, 1, wx.GROW | wx.ALL, 2)
  
          button_next = wx.Button(self, -1, 'Next')
          self.Bind(wx.EVT_BUTTON, self.OnNext, button_next)
          subbox.Add(button_next, 1, wx.GROW | wx.ALL, 2)
  
          self.html_window = wx.html.HtmlWindow(self)
          contents = """\
  <!DOCTYPE html>
  <html>
  <head>
      <title>Welcome to Orbital Academy</title>
  </head>
  <body>
      <h3><center>Welcome to <b>Orbital Academy</b></center></h3>
      <p>Orbital Academy is a place to learn orbital mechanics. The curriculum is organized into lessons
      of progressive difficulty. After you completed them all you will have become an expert spacecraft pilot!</p>
      <br>
      <p>The display on the left shows Earth orbital space.</p>
      <p>You can rotate the view by dragging with the right mouse button, and zoom in and out using the mouse wheel.</p>
      <br>
      <p>Click on a lesson to start your journey!</p>
      <ol>
          <li>Conic Sections</li>
          <li>Orbital Motion</li>
          <li>Orbital Elements - Equatorial Orbits</li>
          <li>Circular Orbits</li>
          <li>Hoffman Transfers</li>
          <li>Six Orbital Elements</li>
          <li>Plane Changes</li>
          <li>Orbital Intercept</li>
          <li>Orbital Rendezvous</li>
      </ol>
  </body>
  </html>
  """
          self.html_window.SetPage(contents)
  
          sizer = wx.BoxSizer(wx.VERTICAL)
          sizer.Add(self.html_window, 1, wx.EXPAND)
          sizer.Add(subbox, 0, wx.EXPAND)
  
          self.SetSizer(sizer)
  
          self.Bind(wx.EVT_CLOSE, self.OnClose)
  
      def OnPrev(self, evt):
          print 'OnPrev'
  
      def OnNext(self, evt):
          print 'OnNext'
  
      def OnRunPause(self, evt):
          print 'OnRunPause'
  
      def OnClose(self, evt):
          self.Destroy()
  
subject: Add lessons list