var message = "The Hong Kong Observatory has announced the issue of the Black Rainstorm Warning Signal at 3:35 p.m. today, 28 July 2010.";
var message = message+"                    ";
var delay   = 150;

function scrollMsg() {
     window.status = message;

     // shift one character
     message = message.substring(1, message.length)+message.substring(0,1);

     // recursive call
     setTimeout("scrollMsg()", delay);
}
// -->

scrollMsg()