old_contents: """ flexx.ui
  
  GUI toolkit based on web technology with a Pythonic API.
  """
  
  from .app import run, stop, App, call_later
  from .app import Mirrored, get_instance_by_id
  
  from .widget import Widget  #, Window
  from .button import Label, Button
  from .layout import Layout, Box, HBox, VBox
  from .layout import BaseTableLayout, FormLayout, GridLayout
  from .layout import Splitter, HSplitter, VSplitter
  from .layout import PinboardLayout
  from .progressbar import ProgressBar
  
new_contents: """ flexx.ui
  
  GUI toolkit based on web technology with a Pythonic API.
  """
  
  from .app import run, stop, App, call_later
  from .app import Mirrored, get_instance_by_id
  
  from .widget import Widget  #, Window
  from .button import Label, Button
  from .layout import Layout, Box, HBox, VBox
  from .layout import BaseTableLayout, FormLayout, GridLayout
  from .layout import Splitter, HSplitter, VSplitter
  from .layout import PinboardLayout
  from .progressbar import ProgressBar
  from .layout2 import Group
  
subject: add progress bar