Python-mode sketch windows not closing properly for Processing 4

[celinelatulipe]

In Python mode for Processing 4, the sketch windows don't close when you stop the sketch using the stop button.

In the screenshot above I ran the sketch, then clicked the Stop button. But the sketch window remains open.
I'm on a MacBook Pro.

[Metamere]

It behaves similarly on Windows. The stop button does halt the draw loop, but the window doesn't close.

[tabreturn]

I recommend using Processing 3.5.4 for Python Mode (at least while Processing 4 is in beta).