Modal

Most foreigners will never fully master the use of German modal particles.

Dialogs can be modal, in which case the user is required to provide necessary information before work in the main window can continue, or modeless. Modeless dialogs do not prevent the user from interacting with any of the other windows in the application.

a modal dialog; a modal window

Using the same type of distributional criterion, we could argue that only a Verb (in its base form) can occur in the position marked — in (23) below to complete the sentence: (23) They/it can — [...] Conversely, the only type of word which could be used to begin a three-word sentence such as (25) below: (25) — I be frank? is a Modal: cf. [...]

Modal screen elements are subtrees which, when activated, disable all elements external to them. Examples of modals are yes-no message boxes and the application itself.