Config attribute of dcc.Graph does not respond to callbacks (is read-only)

When using a callback to control the modebar settings on a chart through the config property of a dcc.Graph, the graph does not update but retains the initial setting.

Note: I have not (yet) tested with other config settings.

Minimal example

import dash
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output, State
import plotly.express as px

app = dash.Dash()
server = app.server

app.layout = html.Div(
    [
        dcc.Graph(
            id="line-graph",
            figure=px.line(x=[1, 2, 3], y=[1, 2, 3]),
        ),
        dcc.RadioItems(
            options=[
                {"label": "Show modebar", "value": 1},
                {"label": "Hide modebar", "value": 0},
            ],
            value=1, # Note that if this value is set to 0 then the modebar will stay turned off rather than turned on.
            id="radio",
        ),
        html.Div([html.H3("Current config"), html.P(id="cur-config")]),
    ]
)


@app.callback(
    [Output("line-graph", "config"), Output("cur-config", "children")],
    [Input("radio", "value")],
)
def toggle_modebar(i):
    vals = [False, True]
    config = {"displayModeBar": vals[i]}
    return config, str(config)


if __name__ == "__main__":
    app.run_server(debug=True, port=8050)

Screen recording

https://user-images.githubusercontent.com/38958867/107691811-edb77d00-6c79-11eb-8488-c750b635f815.mov

Inizia eseguendo l'esempio Python minimo e verificando il callback di dcc.Graph con l'impostazione modebar. Traccia il modo in cui dcc.Graph riceve e applica gli aggiornamenti del callback, quindi verifica che la modifica della selezione radio cambi il comportamento della modebar del grafico, invece di cambiare soltanto la config visualizzata.