Displays a dialog box with
title in the title bar and
message as the message.
The dialog has an "OK" and a "Cancel" button.
Processing does not continue until the user clicks one of these buttons.
The commander window is also disabled until messagebox is dismissed.
If the user presses "OK", then processing continues.
If the user presses "Cancel", then processing is halted, as if by the HALT command.
message inputs must be lists or words.
message input is truncated according to the current values of PRINTWIDTHLIMIT and PRINTDEPTHLIMIT.
The message box is automatically sized to fit
The message is not word-wrapped, so if you have a long message, you may want to put in some line breaks.
MESSAGEBOX [This is the title] [This is the message. Press OK.]