GNU Emacs Lisp Reference Manual

26.16: Dialog Boxes

A dialog box is a variant of a pop-up menu. It looks a little different (if Emacs uses an X toolkit), it always appears in the center of a frame, and it has just one level and one pane. The main use of dialog boxes is for asking questions that the user can answer with ``yes'', ``no'', and a few other alternatives. The functions y-or-n-p and yes-or-no-p use dialog boxes instead of the keyboard, when called from commands invoked by mouse clicks.

Function: x-popup-dialog position contents

This function displays a pop-up dialog box and returns an indication of what selection the user makes. The argument contents specifies the alternatives to offer; it has this format:

(title (string . value)...)

which looks like the list that specifies a single pane for x-popup-menu.

The return value is value from the chosen alternative.

An element of the list may be just a string instead of a cons cell (string . value). That makes a box that cannot be selected.

If nil appears in the list, it separates the left-hand items from the right-hand items; items that precede the nil appear on the left, and items that follow the nil appear on the right. If you don't include a nil in the list, then approximately half the items appear on each side.

Dialog boxes always appear in the center of a frame; the argument position specifies which frame. The possible values are as in x-popup-menu, but the precise coordinates don't matter; only the frame matters.

If your Emacs executable does not use an X toolkit, then it cannot display a real dialog box; so instead it displays the same items in a pop-up menu in the center of the frame.