olemus
algses aknas avanev sekundaaraken, mis
blokeerib algse akna juhtimise ja nõuab kasutaja sekkumist
=
an interface element that displays in front of and deactivates all other page content, a graphical control element subordinate to a main window

ülevaateid
https://www.quora.com/What-is-the-difference-between-a-modal-window-and-a-pop-up-window

https://blog.hubspot.com/website/modal-web-design

https://en.wikipedia.org/wiki/Modal_window

https://www.smashingmagazine.com/2009/05/modal-windows-in-modern-web-design/