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The problem is that when a dialog is closed, it exits its event loop (the one launched with exec) with a Rejected result.

In your case, since the rejection doesn't match window.exec_() == QDialog.Accepted, the result is that that whole block is not evaluated, and the application simply exits.

A simple solution would be to hide the login until the registration is completed (or rejected) and show it again afterwards.

Since the login dialog should be shown anyway, there's no need for custom signals or if statements, as it's enough to call the registration dialog's exec_ in the redirect_to_register function, so that you can show again the login no matter the result of the registration.

Unfortunately, there's a problem with that: in Qt, hiding a dialog results in a behavior similar to closing it (so, rejecting).
The solution is to avoid the base implementation of QDialog (which overrides both hide() and setVisible()), and use that of QWidget instead:

If either one of your params is null, then you will only be creating one cell in the row. Your table always needs two cells to match the two headings you have.

There are various ways around this. The following is one way, which I think is reasonably concise:

Your idea to keep an array of checked items is close, though I'd suggest using a map so you have O(1) constant time lookups of checked item status.

Keep a map of checked item id's, the onChange passes the input id and checked value, and the id is used to retrieve the checked value.

Update handleIndividualCheck to destructure checked and input id from the event and update the checked state.