[whatwg] prompts, alerts and showModalDialog during beforeunload/unload events

[João Eiras]

>> Though I'm not sure what exactly Ojan is proposing we forbid?
>
> I think his suggestion is to forbid all of window.prompt, window.alert,  
> and window.showModalDialog. Persumably window.confirm as well.
>

Exactly. But we don't need a spec to tell that. It's 100% user agent  
feature, so you're free to have better or worse UI. Same could be said  
when the user right-clicks.