In Mathematica, dialog boxes are customized notebooks used to provide users with information and/or request user input.

There are two properties associated with dialogs.

A modal dialog forces the user to respond to the dialog before doing anything else. This allows the front end to acquire the information necessary to either complete or initiate an evaluation. For example, when most applications close, a modal dialog will appear, prompting the user to save changes. Since the response is crucial in determining how the application should close, the dialog will prevent access to the other parts of the program until the user has responded to it. Setting the option Modal ->True will make a dialog modal.

Note: Modal dialogs will prevent users from accessing other notebooks in the front end while the dialog is open. If there is no mechanism for closing the dialog, Mathematica will effectively freeze.

A blocking dialog halts a running evaluation until the user responds to it, but does not prevent access to other parts of the front end. The kernel in which these dialogs are evaluated will effectively block until the dialog is closed. For example, a choice dialog will start an evaluation, wait until the user chooses a value, and then complete the evaluation by returning the value. Any other evaluations that are sent through the main link while the dialog is open will be queued and evaluated once the dialog is closed.

Some dialogs are neither modal nor blocking, such as the system find dialog and message dialogs.

Dialogs typically include buttons to allow users to respond to a question, a message, or other requested input. One of these buttons is the default action and is highlighted when the dialog opens. Another button that is almost always present is the cancel button, which will close the dialog and abort the dialog's action.

In Mathematica, the default and cancel buttons can be created using a series of streamlined functions.

In dialogs created using DialogInput or CreateDialog , pressing Enter is equivalent to clicking the OK (default) button and pressing Esc is equivalent to clicking the Cancel button. If there are several default buttons in a single dialog, Enter will use the first one in the dialog. Similarly, pressing Esc will use the first Cancel button in the dialog.

Create a cancel button and a default button in a row.

ChoiceButtons will display the default and cancel buttons in the standard order for the current computer system.

Dialog notebooks can be opened as a separate window in the front end as a notebook or in-cell expression. Dialog notebooks are non-blocking dialogs that may or may not be modal.

Note: Modal dialogs will prevent users from accessing other notebooks in the front end while the dialog is open. If there is no mechanism for closing the dialog, Mathematica will effectively freeze.

Here is a dialog that displays a notification or message.

Set Modal ->True to make the same dialog modal.

Alternatively this creates an in-cell representation of the dialog notebook. A separate window containing the notebook can be opened in the front end by clicking the {}[[3]] button or wrapping CreateDialog around the DialogNotebook expression.

Dialogs that display a message can also be created using MessageDialog , which includes the DefaultButton by default.

Here is a message dialog informing a user that a calculation is complete.

Sometimes it is useful to also include an audible beep with the message dialog using Beep .

In addition to accepting input, dialog boxes can also evaluate expressions when they are closed. This can be done using DialogReturn . Here is a modal dialog box that accepts user input and evaluates a variable assignment.

Type a first and last name into the input fields and click OK to assign the input values to name.

Several front end dialogs such as the Mathematica Preferences dialog were created using CreateDialog .

The kernel in which blocking dialogs are evaluated is blocked until the dialog is closed.

Block the kernel until val is set to 123.

Here, the kernel is blocked until the user sets a value to removeQ by selecting Cancel or OK.

Dialogs that display a choice can also be created using ChoiceDialog , which blocks the kernel and returns False if the CancelButton is selected or True if the DefaultButton is selected.

If the blocking dialog is thrown by a button or action menu, pass the button action along the main link to prevent timing out. This can be done by setting Method .

Mathematica also offers access to system dialog through the use of SystemDialogInput , front end tokens, and user interface-specific button functions including FileNameSetter , ColorSlider , and ColorSetter .

Here is the system file open dialog that returns the file path for the chosen file.

exhibits the same behavior as by returning the file path for the chosen file.

This opens the system color dialog and returns the RGBColor value for the selected color.

The front end token opens the system print dialog and prints the notebook when the user selects Print.

Here is a button that opens the system file open dialog and assigns the file path for the chosen file to a dynamic variable.

calls the system multiple file open dialog instead.

exhibits the same behavior as by assigning the file path for the chosen file to a dynamic variable.

This creates a button that opens the system directory picking dialog and assigns the file path for the chosen directory to a dynamic variable.

Here is a color swatch that can be used to assign the value of a dynamic variable to an RGB color. Clicking the swatch will open the system color picker dialog.

ColorSlider is a control object that contains the ColorSetter swatch as well as a color spectrum. Double-clicking the spectrum will open the system color picker dialog.

Mathematica usually works by taking whatever input it is given and then processing it. Sometimes, however, programs may need to explicitly request more input. This can be done using Input and InputString .

Note: With a text-based interface, Input and InputString will just wait for standard input, terminated by a newline. See "Requesting Input" for more information.

This returns the polynomial expansion of the input.

Here the inputted string is split into a list of substrings.

Here is a progress dialog that tracks the value of the dynamic variable during a computation.

This is a modal dialog that will save the inputted notebook if the user selects Save or abort the operation if the user instead chooses Cancel.

This next example is a find dialog similar to those found in many applications.

Mathematica can track the amount of memory being used by the front end and kernel processes at any given time. Here is a dialog that displays that data in real time.