1. Dialog element

    Method of easily creating custom dialog boxes to display to the user with modal or non-modal options. Also includes a `::backdrop` pseudo-element for behind the element.

  2. accept attribute for file input

    Allows a filter to be defined for what type of files a user may pick with from an `<input type="file">` dialog

  3. BeforeUnloadEvent API: User interaction required for dialog box

  4. HTMLDialogElement API

  5. HTMLDialogElement API: `cancel` event

  6. HTMLDialogElement API: close

  7. HTMLDialogElement API: `close` event

  8. HTMLDialogElement API: open

  9. HTMLDialogElement API: returnValue

  10. HTMLDialogElement API: show

  11. HTMLDialogElement API: showModal

  12. Window API: openDialog

  13. Window API: showModalDialog

  14. CSS selector: `::backdrop`: Support on `dialog` elements

  15. HTML element: dialog

  16. HTML element: dialog: open