Describe the bug
Notebook scrolls when using PanZoom after clicking any buttons on Toolbar.

To Reproduce
When I run code cell with plot for the first time, everything works fine. But when I click on any button from Toolbar and then click again on PanZoom button, notebook starts scrolling when zooming plot.

You can use this code to reproduce the bug:

from bqplot import *
from IPython.display import display

x_data = range(10)
y_data = [i ** 2 for i in x_data]

x_sc = LinearScale()
y_sc = LinearScale()

ax_x = Axis(label='Test X', scale=x_sc, tick_format='0.0f')
ax_y = Axis(label='Test Y', scale=y_sc,
            orientation='vertical', tick_format='0.2f')

line = Lines(x=x_data,
             y=y_data,
             scales={'x': x_sc, 'y': y_sc},
             colors=['red', 'yellow'])

fig = Figure(axes=[ax_x, ax_y], marks=[line])

tb = Toolbar(figure=fig)

display(fig)
display(tb)

Expected behavior
Only plot should scroll when mouse hovers it.

Additional context
Bug was reproduced with next setups:

1. Jupyter Lab 3.0.16 running on Windows 7 with bqplot 0.12.27 and Python 3.8.10. I tried to use it with:
   Edge 91.0.864.37 (Official build) (64-bit) from Win 7 PC and remotely from Win 10 and macOS 11.4;
   Chrome 91.0.4472.77 (Official Build) (64-bit) from Win 7 PC;
   Chrome 90.0.4430.0 (Developer Build) (64-bit) remotely from Win 10;
   Safari 14.1.1 (16611.2.7.1.4) remotely from macOS 11.4.
2. Jupyter Lab 3.0.10 running on Windows 10 with bqplot 0.12.27 and Python 3.9.5. I tried to use it with Edge 91.0.864.37 (Official build) (64-bit) from Win 10;

I've already seen Pull request #1347, but I don't think it fixed this problem, because I tried to use bqplot 0.12.25, 0.12.26 and 0.12.27.