from tkinter import *
import numpy as np
import matplotlib
matplotlib.use("Agg")
import matplotlib.pyplot as plt
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg

mainWindow = Tk()

fig = plt.figure()
ax = fig.add_subplot(1,1,1)
img = ax.imshow(np.random.rand(28,28), cmap="gray", interpolation="None")
fig.canvas.draw()

canvas = FigureCanvasTkAgg(fig, master=mainWindow)
canvas.draw()
canvas.get_tk_widget().grid(row=1, column=1)

def openPopup():
    popup = Tk()

    popupCanvas = FigureCanvasTkAgg(fig, master=popup)
    popupCanvas.draw()
    popupCanvas.get_tk_widget().grid(row=1, column=1)

    popup.protocol("WM_DELETE_WINDOW", popup.destroy)
    popup.mainloop()

def doBlit():
    img.set_data(np.random.rand(28,28))
    ax.draw_artist(img)
    
    fig.canvas.blit(ax.bbox) # this blit line is the cause of the crash

    fig.canvas.flush_events()

button_1 = Button(mainWindow,command=(openPopup),text="open popup")
button_1.grid(row=1,column=2)
button_2 = Button(mainWindow,command=(doBlit),text="do blitting")
button_2.grid(row=1,column=3)

mainWindow.mainloop()