Bug summary

I tried doing pip install pyside6 and using matplotlib and a chart window appears, but just hangs.

Code for reproduction

import matplotlib as mpl
import matplotlib.pyplot as plt

mpl.use('QtAgg') # 'QT5Agg' also fails, 'TkAgg' works.

plt.plot([1, 2, 3, 2, 3, 4])

plt.show()

Actual outcome

Chart window opens and hangs.

Expected outcome

Should work the same as when the backend is TkAgg.

Additional information

I'm running the code in IntelliJ and everything worked fine before I installed Qt.

I'm a newbie and a bit confused as to what exactly I need to do to use Qt as a backend. Note that I'm just exploring/learning, I don't have a reason to want to use Qt over Tk or anything else.

I've read this page on Qt bindings (the text on this page doesn't show up in the actual docs)

And also saw #19255 that seems to add support and was merged and I'm using a later version 3.5.2.

And I've read this page in the docs and it seems to imply (but not say) that all I need to do is install PySide6 and it should work.

Weirdly, if I just use the code:

import matplotlib.pyplot as plt

plt.plot([1, 2, 3, 2, 3, 4])

plt.show()

It works, which is weird for two reasons:

1. This means that just importing matplotlib invokes different behaviour to importing matplotlib.pyplot.
2. Not importing matplotlib directly (only pyplot) results in the message "Backend MacOSX is interactive backend. Turning interactive mode on.". Weird as I'm on Windows, and if I then run plt.get_backend() it says QtAgg. It's all so confusing!

Operating system

Windows 11

Matplotlib Version

3.5.2

Matplotlib Backend

QtAgg, Qt5Agg

Python version

3.10.2

Jupyter version

No response

Installation

pip