Dialog box

The graphical control element dialog box (also called dialogue box or just dialog) is a small window that communicates information to the user and prompts them for a response.

Dialog boxes are classified as "modal" or "modeless", depending on whether they block interaction with the software that initiated the dialog. The type of dialog box displayed is dependent upon the desired user interaction.

The simplest type of dialog box is the alert, which displays a message and may require an acknowledgment that the message has been read, usually by clicking "OK", or a decision as to whether or not an action should proceed, by clicking "OK" or "Cancel". Alerts are also used to display a "termination notice"—sometimes requesting confirmation that the notice has been read—in the event of either an intentional closing or unintentional closing ("crash") of an application or the operating system. (, "Gedit has encountered an error and must close.") Although this is a frequent interaction pattern for modal dialogs, it is also criticized by usability experts as being ineffective for its intended use, which is to protect against errors caused by destructive actions, and for which better alternatives exist.

An example of a dialog box is the about box found in many software programs, which usually displays the name of the program, its version number, and may also include copyright information.

Non-modal or modeless dialog boxes are used when the requested information is not essential to continue, and so the window can be left open while work continues elsewhere. A type of modeless dialog box is a toolbar which is either separate from the main application, or may be detached from the main application, and items in the toolbar can be used to select certain features or functions of the application.

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