var Status = "none";

function ChangeStatus(NewStatus) { 
    var ButtonUp = document.getElementById("up"), ButtonDown = document.getElementById("down");

    if(NewStatus == "down") {
        Status = "down";
        ButtonDown.src = "images/arrow_down.jpg";
        ScrollDown();
    } else if(NewStatus == "up") {
        Status = "up";
        ButtonUp.src = "images/arrow_up.jpg";
        ScrollUp();
    } else {
        Status = "none";
        ButtonUp.src = "images/arrow_up.jpg";
        ButtonDown.src = "images/arrow_down.jpg";
    }
}

function ScrollUp() {
    if(Status == "up")
    {
        document.getElementById("scrolling_content").scrollTop -= 10;
        setTimeout(function() { ScrollUp(); }, 50);
    }
}

function ScrollDown() {
    if(Status == "down")
    {
        document.getElementById("scrolling_content").scrollTop += 10;
        setTimeout(function() { ScrollDown(); }, 50);
    }
}