Message

Use a message to report unexpected or undesirable situations to the user that require some user action or decision.

Use a message to indicate that a task has completed successfully, but there is additional information available about the completion status of the task.

Use a message to indicate that a process is in progress.

Phrase message text so that a user clearly understands what caused the message as well as what action, if any, can be taken to correct the situation that caused the message.

When wording the messages displayed by your application, do not assume that the user has any expert knowledge about computer systems in general or the operating system in particular. You can assume that the user has knowledge about basic interface terms that could have been learned through tutorials, help information, and user documentation. However, avoid terminology that is typically understood only by an expert or knowledgeable computer user unless the application is specifically targeted at computer professionals. Also, messages returned to your application by the underlying system should not be passed directly to the user, but instead should be interpreted into language the novice user can understand.

Avoid phrasing messages in a way that requires a Yes or No response from the user. If you use Yes and No push buttons, avoid using negatives in the message text. For example, do not use the message:

Are you sure you don't want to save the file?

Instead, use:

File has been modified.
Choose `Discard' to throw away changes or 
`Save' to save the file and then quit.

If a window associated with the task or element for which the task is being performed is open, display the message in a secondary window that depends on the associated window.

If no associated window is open for a task being performed and for which an urgent message must be displayed, then display the message in a secondary window and, optionally, display the task's window if such a window exists.

If no associated window is open for the task being performed and for which a nonurgent message needs to be displayed, then place the message in a secondary window, but do not display it. Optionally, change the appearance of the icon through which the window can be displayed if such a window exists.

If you provide a message identifier in a message window, place it in the bottom rightmost corner of the message and display it in a smaller font than the rest of the message text. For information on bidirectional and vertical language support, see Chapter 11.

Provide a Help push button in all messages, except those that contain trivial or self-explanatory messages. Design your application with both the expert and novice user in mind. The novice user must be able to access additional explanatory information, the circumstances under which it was displayed, and what the user should do in response to the message.

Use Table 17 “Push Buttons for Various Message Types” to determine which predefined push buttons to use in messages.