The message widget displays a long text string by formatting it onto several lines. It is designed for use in dialog boxes. It can format the text into a box of a given width, in screen units, or a given aspect ratio. The aspect ratio is defined to be the ratio of the width to the height, times 100. The default is 150, which means that the text will be one and a half times as wide as it is high.
Example 29-3 creates a message widget with one long line of text. Backslashes are used to continue the text string without embedding any newlines. (You can also just type a long line into your script.) Note that backslash-newline collapses white space after the newline into a single space.