Bug report

Bug summary
WebAgg blocks python code at plt.show(block=False)

plt.show(block=False) should not block code execution
Code for reproduction
import matplotlib as mpl
mpl.use('WebAgg')
#mpl.use('WXAgg')
import matplotlib.pyplot as plt
from matplotlib.pyplot import plot, ion, show
ion() # enables interactive mode

do your plotting

import numpy as np
a=np.random.random(100)
b=np.random.random(100)
plt.plot(a,b)
#plt.draw()
plt.show()
#plt.show(block=False)

q=0

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Actual outcome

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Expected outcome

Matplotlib version

• Operating system:
• Matplotlib version:
• Matplotlib backend (print(matplotlib.get_backend())):
• Python version:
• Jupyter version (if applicable):
• Other libraries: