docs: def _graphics_equal(gfx1, gfx2):
      '''
      Test if two graphics devices should be considered the same device
      '''
      def _filter_graphics(gfx):
          '''
          When the domain is running, the graphics element may contain additional properties
          with the default values. This function will strip down the default values.
          '''
          gfx_copy = copy.deepcopy(gfx)
  
          defaults = [{'node': '.', 'attrib': 'port', 'values': ['5900', '-1']},
                      {'node': '.', 'attrib': 'address', 'values': ['127.0.0.1']},
                      {'node': 'listen', 'attrib': 'address', 'values': ['127.0.0.1']}]
  
          for default in defaults:
              node = gfx_copy.find(default['node'])
              attrib = default['attrib']
              if node is not None and (attrib not in node.attrib or node.attrib[attrib] in default['values']):
                  node.set(attrib, default['values'][0])
          return gfx_copy
  
      return ElementTree.tostring(_filter_graphics(gfx1)) == ElementTree.tostring(_filter_graphics(gfx2))