figures that start in background tabs are cut off at bottom

I'm having some trouble with figures getting cut off at the bottom when they're included in tabs other than the first tab. Here's a minimal example. Note that I put the figures in boxes because I have the same problem as #126 if I don't.

%matplotlib widget
import matplotlib.pyplot as plt
plt.ioff()
import ipywidgets as widgets
import numpy as np
fig1,ax1 = plt.subplots()
ax1.scatter(np.arange(10),np.random.random(10))
ax1.set_xlabel('x axis')
ax1.set_ylabel('y axis')
fig2,ax2 = plt.subplots()
ax2.plot(np.arange(10),np.random.random(10))
ax2.set_xlabel('x axis')
ax2.set_ylabel('y axis')
tabs = widgets.Tab(children=[widgets.Box([fig1.canvas]),widgets.Box([fig2.canvas])])
tabs.set_title(0, 'fig1')
tabs.set_title(1, 'fig2')
tabs

The first tab looks like (I clicked on the figure to show the boundaries)

and the second tab looks like:

I just cannot figure out why the bottom of that second figure is getting cut off.

Inizia eseguendo l'esempio minimo di notebook con due schede ipywidgets e figure matplotlib, quindi confronta le dimensioni della seconda figura, inizialmente nascosta, con quelle della prima. Traccia il modo in cui vengono stabilite le dimensioni della figura quando la seconda scheda diventa visibile. Il lavoro è completato quando le figure in ogni scheda mostrano l'intera area del grafico senza essere tagliate.