If $bounce is true, the text will scroll to the left until the first character hits the left edge of the visible window then it will scroll back to the right. When the last character hits the right edge of the visible window the text will scroll back to the left again.
If all of the scrolling text cannot be viewed at once, making the text bounce will have an undesired result. Therefore it is suggested that the length of the text always be at least one character less than the maximum viewable string length.