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: dialogarguments

  13. window api: opendialog

  14. window api: showmodaldialog

  15. css selector: `::backdrop`: support on `dialog` elements

  16. html element: dialog

  17. html element: dialog: open