Bug summary

I've been adding annotations following the excellent examples at AnnotationBbox demo, but I'd like to make the text box transparent. From the TextArea docs it looks like my_text_area.set(alpha=x) should work, but it doesn't seem to have any effect.

Perhaps there is another way to set this that I have missed?

Code for reproduction

import matplotlib.pyplot as plt
from matplotlib.offsetbox import TextArea, AnnotationBbox

import numpy as np

rng = np.random.default_rng()

data = rng.normal(size=30)

plt.rcdefaults()

_ , ax = plt.subplots()
ax.hist(data)

offsetbox = TextArea('Look over there!')
offsetbox.set(alpha=0.3)

ab = AnnotationBbox(offsetbox, (0.8, 0.8),
            xybox=(0, 1),
            xycoords='axes fraction',
            boxcoords='data',
            arrowprops=dict(arrowstyle="->"))

ax.add_artist(ab)

plt.show()

Actual outcome

Expected outcome

The text box should be transparent.

Additional information

I tried a few versions back to 3.3, but the result was the same.

Operating system

RHEL7

Matplotlib Version

3.6.2

Matplotlib Backend

QtAgg

Python version

3.8.13

Jupyter version

N/A

Installation

conda