Dialogs are container widgets that provide a means of communicating between the user and the application. A dialog widget usually asks a question or presents some information to the user. In some cases, the application is suspended until the user provides a response.
Dialogs are similar to menus. Both seek input from the user. Like PopupMenus and PulldownMenus, dialogs appear in top-level windows and are more or less transient. Making a selection typically unposts a PopupMenu or PulldownMenu and often pops down a dialog. "PopupMenu" "in DialogBoxes" "PulldownMenu" "in DialogBoxes" There are two chief differences:
Menus are well suited to allowing the user to make a single choice from a constrained set. Dialogs are appropriate for displaying information about a transient or unusual state of the program and for obtaining complex input from the user. Whether to use a dialog or a menu is not always clear. In fact, a TearOffMenu combines aspects of both. For more information on using menus and dialogs, see the Motif Style Guide.