figures that start in background tabs are cut off at bottom

[keatonb]

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.