// Return the available content height space in browser window
// http://markmail.org/message/s6acrjd4ny2skkx5
$.viewportHeight = function() {
     var h = 0;
     if (typeof(window.innerHeight) == "number") {
         h = window.innerHeight;
     } else {
         if (document.documentElement && 
document.documentElement.clientHeight) {
             h = document.documentElement.clientHeight;
         } else {
             if (document.body && document.body.clientHeight) {
                 h = document.body.clientHeight;
             }
         }
     }
     return h;
}