Nesting into HBox collapses plot width

Here's another effect of requiring the canvas size explicitly, but somehow isn't visible unless the plot gets dropped into an ipywidgets layout (e.g. by a downstream package).

If the interactive matplotlib is the child of one p-Panel, it's fine. But gets squashed as the child of two p-Panels (regardless of orientation).

Explicitly setting canvas.layout.width fixes it, and propagates to the front-end as expected.

from ipywidgets import HTML, HBox, VBox
from matplotlib.figure import Figure
from ipympl.backend_nbagg import Canvas, FigureManager

figure = Figure()
canvas = Canvas(figure)
canvas.manager = FigureManager(canvas, 0)

axes = figure.add_subplot(1,1,1)
HBox([HBox([HTML(''), canvas])])

HBox([canvas])

Comienza con el reproductor de Canvas/FigureManager proporcionado en un notebook, comparando un canvas en un HBox con el mismo canvas anidado en dos HBoxes. Investiga cómo se propaga el tamaño del canvas a los layouts de ipywidgets; se considera terminado cuando el gráfico conserva su anchura al anidarse sin establecer explícitamente canvas.layout.width.