Issue with porting ipkernel_qtapp to PySide6, event loop doesn't quit

[jeandet]

Hello,

I was successfully using in process embedded QtConsole example in my app.
Now, I want to allow jupyter notebooks to connect to my app kernel, so I switched to IPKernelApp like in this example but I can't close anymore My app.
The trick that work is to call quit() from the kernel with self.ipkernel.shell.run_cell("quit()") or from a QtConsole, using qapp.quit() doesn't seems to work anymore.
Here is a patch if someone want to reproduce the issue with ipykernel example:
ipykernel_pyside6.zip