The MessageDialog dialog element defines a message dialog in a Maplet application. This dialog contains a caption and an OK button.

Maplets dialog elements have a predefined layout.  For a dialog, an author cannot specify elements.  This is different from the Window element, which can contain other elements, for example, buttons and layout elements.

The Message element features can be modified by using options. To simplify specifying options in the Maplets package, certain options and contents can be set without using an equation. The following table lists elements, symbols, and types (in the left column) and the corresponding option or content (in the right column) to which inputs of this type are, by default, assigned.

A MessageDialog element can contain Action or command elements to specify the onapprove option.

A MessageDialog element can be contained in a Maplet element.

The following table describes the control and use of the MessageDialog element options.

An x in the I column indicates that the option can be initialized, that is, specified in the calling sequence (element definition).

An x in the R column indicates that the option is required in the calling sequence.

An x in the G column indicates that the option can be read, that is, retrieved by using the Get tool.

An x in the S column indicates that the option can be written, that is, set by using the SetOption element or the Set tool.

The opts argument can contain one or more of the following equations that set Maplet application options.

caption = string or symbol

The text that appears in the body of the message dialog.

height = posint

The window height in pixels.

onapprove = Action or command element, or reference to an Action element (name or string)

The action that occurs when the user clicks the OK button or the dialog close button on the title bar. By default, the action shuts down the dialog.

reference = name or string

A reference for the MessageDialog element.

If the reference is specified by both an index, for example, MessageDialog[refID], and a reference in the calling sequence, the index reference takes precedence.

resizable = true or false

Whether the user can resize the window.  By default, false.

title = string or symbol

The text that appears in the title bar of the message dialog. The default title is Message.

type = `error`, information, plain, or warning

Displays an icon associated with the caption.  By default, a plain message dialog is used which does not display an icon.

width = posint

The window width in pixels.

$\mathrm{with}\left(\mathrm{Maplets}\left[\mathrm{Elements}\right]\right)\:$

$\mathrm{maplet}≔\mathrm{Maplet}\left(\mathrm{MessageDialog}\left(\mathrm{warning}\,''Contradictory\; assumptions\; on\; `x`''\,'\mathrm{onapprove}'=\mathrm{Shutdown}\left(\right)\right)\right)\:$

$\mathrm{Maplets}\left[\mathrm{Display}\right]\left(\mathrm{maplet}\right)$