Can BackgroundPlotter refresh and redraw in a loop?

[rruixxu]

I just want to draw a sequence of different mesh and implement it in a loop by BackgroundPlotter. But I have tried my best to figure out how to do that.
In the following code, I have to place plotter.app.exec_() at the end of the loop to realize interactive zoom in and pan. However, the window will not go on to the next iteration. I tried to place input() or sleep() at the end of the loop, but making window non-interactive then.
I just want to simulate the window behavior of opencv which can block the iteration util I press some keys or util certain time. How can I do that?

import pyvista as pv
from pyvistaqt import BackgroundPlotter

sphere = pv.Sphere()
scale = 2

plotter = BackgroundPlotter()
for i in range(4):
    plotter.clear()
    sphere.points *= scale
    plotter.add_mesh(sphere)
    plotter.app.exec_()