VegaFusionWidget regressions with Altair 5

[jonmmease]

Consider the following example:

import pandas as pd
import altair as alt
import vegafusion as vf

vf.enable_widget()

flights = pd.read_parquet(
    "https://vegafusion-datasets.s3.amazonaws.com/vega/flights_1m.parquet"
)

brush = alt.selection(type='interval', encodings=['x'])

# Define the base chart, with the common parts of the
# background and highlights
base = alt.Chart().mark_bar().encode(
    x=alt.X(alt.repeat('column'), type='quantitative', bin=alt.Bin(maxbins=20)),
    y='count()'
).properties(
    width=160,
    height=130
)

# gray background with selection
background = base.encode(
    color=alt.value('#ddd')
).add_selection(brush)

# blue highlights on the selected data
highlight = base.transform_filter(brush)

# layer the two charts & repeat
chart = alt.layer(
    background,
    highlight,
    data=flights
).transform_calculate(
    "time",
    "hours(datum.date)"
).repeat(column=["distance", "delay", "time"])
chart

With Altair 4.2, a selection on the distance histogram results in the following

But with Altair 5.0.0rc1, the background histograms for the distance and delay subplots disappears:

I haven't dug in yet to diagnose where the breakdown is.

[jonmmease]

Looks like the same issue crops up in the Altair 5 gallery example without VegaFusion: https://altair-viz.github.io/gallery/interactive_layered_crossfilter.html

[jonmmease]

This is a known issue already tracked in vega/altair#2849