AFAIK, it is based on the word "mode", because what's supposed to happen is the rest of the page is disabled while you deal with the modal. You've switched modes from "normal usage" to "the popup".

If you can still interact with some other part of the page while it's open, it's not a modal, it's just a popup.

It's a term from the UI design world, and it goes way back. A mode is a state where the app accepts certain inputs from you, the user. A new mode means previous buttons and shortcuts are inaccessible, and the same input may produce different results. Either coincidentally or directly related, Vim's modes illustrate the idea well—in contrast to editors where input, motion and shortcuts for extra functions are available together.

https://en.wikipedia.org/wiki/Mode_(user_interface) and https://en.wikipedia.org/wiki/Modal_window

The trouble with elaborate modes is that the user has to mentally keep track of which mode they're in (which is what the term describes); and that other functions are inaccessible even though they might be useful to resolve the situation. However, modal dialogs are a streamlined and visually distinct extreme of modes, with an established history, so some don't consider them problematic. (Modes that are difficult to notice are still a no-no.) OTOH dialogs are frequently used as cheap bail-out by programmers, especially in desktop interfaces—since they're very easy to produce, completely synchronous, and shift all problems onto the user.

Thanks for that explanation.

I guess I just have to live with it when I pop in and out of the UI coding world. Just like in Python a .method isn't what the natural word typically means, but just has gotten a domain-specific meaning attached to it in that world.

Just because you cant see the connection doesnt mean its not there.

Adjective, (of a proposition) in which the predicate is affirmed of the subject with some qualification, or which involves the affirmation of possibility, impossibility, necessity, or contingency.

Its pretty plain to see how a confirm or error message is applied to that definition no?

Not really. It's a stretch (at least for me) to see the connection between a window that shows you some data, or a toggle, or some arbitrary information and the idea that the window should be called "modal" as if it controls some "mode".

Youre misunderstanding that definitions position if you think it has something to do with modes.

> in which the predicate is affirmed of the subject with some qualification,

E.g. an error with an error message

Or

> or which involves the affirmation of possibility, impossibility, necessity, or contingency.

E.g. an are you sure? dialog preceeding a save.

You're radically misunderstanding that definition.

It has to do with the notions that are expressed by "can, should, might, must, has to" etc. These words (most of them are called "modal verbs" in English) modify a proposition in such a way that they do not mean it happened/happens/whatever, but qualify it, or indicate its possibility etc. So "he's going out now" is a proposition. "He can go out now" modifies that proposition - no longer are we affirming it, but merely affirming the possibility or permissability of it.

Nothing about "are you sure" is modal. A modal dialog is called modal because the mode of the program has changed - no longer can it accept requests to delete articles or add text or modify an avatar, but it is now in a mode when you can either say "delete this" or "don't delete this".

In particular, if you showed an inline prompt that says "are you sure? delete/cancel" but still allows you to interact with the rest of the system, it's not modal.