Problem

When I have a notebook open and select "Close and Shut Down Notebook" from the "File" menu of the notebook interface, notebook (as of v. 7.3.0a0) closes the kernel unconditionally, discarding the computational state. I recommend that the interface confirm that the user wants to close and shut down, as JupyterLab does (at least in v. 4.3.0a0) when one selects its "Close and Shut Down Notebook…" menu item.

Proposed Solution

Restore the confirmation dialog and add an ellipsis to the end of the text in the menu item.

Additional context

This behavior seems to have arisen in #7384.