var thumbSlideStep = 5; 
var thumbSlideInterval = 19; 
var clipperHeight = 260/*actual clipper height*/ + 30 /*position corrector*/ ;
var initialOffset = -63; //same as 'top:' value in #scrollbox css

var strip;
var  iMoveD;
var  iMoveU;
var scrollOffset = initialOffset;
strip = document.getElementById('scrollbox');
upHot = document.getElementById('scrollup');
downHot = document.getElementById('scrolldown');

function scrollUp() {
	iMoveU = setInterval('jumpUp()', thumbSlideInterval);  
   }
function scrollDown() {
	iMoveD = setInterval('jumpDown()', thumbSlideInterval); 
   }
function jumpUp() {
	parent.document.body.backgroundImage = "url('images/scrollDown.png')";
	downHot.style.backgroundImage = "url('images/scrollDown.png')";
	downHot.style.cursor = "pointer"; 
   if (scrollOffset > - 1 * (strip.offsetHeight - clipperHeight)) { 
      scrollOffset -= thumbSlideStep; 
      strip.style.top = scrollOffset + "px";
                 }
    else {
    upHot.style.backgroundImage = "url('images/scrollUpGray.png')";
    upHot.style.cursor = "default";
    
    }       
   }
function jumpDown() {
upHot.style.backgroundImage = "url('images/scrollUp.png')"; 
upHot.style.cursor = "pointer"; 
   if (scrollOffset < 0) {
      scrollOffset += thumbSlideStep;
      strip.style.top = scrollOffset + "px";
              }
     else {
    downHot.style.backgroundImage = "url('images/scrollDownGray.png')";
    downHot.style.cursor = "default";
    
    }     
   }
function stopScroll() {

   if(iMoveU) {
      clearInterval(iMoveU); 
      }
     if(iMoveD) {
      clearInterval(iMoveD); 
      }
     
   
   }