Bug summary

I was playing with @timhoffm's new example at #28546 and found that, with QtAgg, when I hit the "configure subplots" button the image subplots immediately move downwards.

Code for reproduction

import matplotlib.pyplot as plt
import numpy as np

from matplotlib import colors

np.random.seed(19680801)

datasets = [
    (i+1)/10 * np.random.rand(10, 20)
    for i in range(4)
]

fig, axs = plt.subplots(2, 2)
fig.suptitle('Multiple images')

# create a single norm to be shared across all images
norm = colors.Normalize(vmin=np.max(datasets), vmax=np.min(datasets))

images = []
for ax, data in zip(axs.flat, datasets):
    images.append(ax.imshow(data, norm=norm))

fig.colorbar(images[0], ax=axs, orientation='horizontal', fraction=.1)

plt.show()

Actual outcome

Initially I get the expected plot

but when I hit the "Configure subplots" button, without changing any subplot settings I have

Expected outcome

Subplots don't move until I tell them!

Additional information

I have reproduced this back to v3.6.3 with QtAgg (I haven't tested further back). I cannot reproduce with TkAgg.

Operating system

Ubuntu

Matplotlib Version

main, 3.8.4, 3.6.3

Matplotlib Backend

QtAgg

Python version

3.9.19, 3.12.3, 3.11.6

Jupyter version

N/A

Installation

conda