old_contents: import hippo
  import gtk
  
  class Window(gtk.Window):
      def __init__(self, window_type=gtk.WINDOW_TOPLEVEL):
          gtk.Window.__init__(self, window_type)
  
          self._canvas = hippo.Canvas()
          self.add(self._canvas)
          self._canvas.show()
  
          self._canvas.connect_after('realize', self._window_realize_cb)
  
      def set_root(self, root):
          self._canvas.set_root(root)
  
      def _window_realize_cb(self, canvas):
          canvas.window.set_back_pixmap(None, False)
  
new_contents: import hippo
  import gtk
  
  from sugar.graphics import color
  
  class _Style(gtk.Style):
      __gtype_name__ = 'SugarCanvasStyle'
      def __init__(self):
          gtk.Style.__init__(self)
  
      def do_set_background(self, window, state):
          window.set_back_pixmap(None, False)
  
  class Window(gtk.Window):
      def __init__(self, window_type=gtk.WINDOW_TOPLEVEL):
          gtk.Window.__init__(self, window_type)
  
          self._canvas = hippo.Canvas()
          self._canvas.set_style(_Style())
          self.add(self._canvas)
          self._canvas.show()
  
      def set_root(self, root):
          self._canvas.set_root(root)
  
subject: Use a custom style to get rid of the damned window background