var widthTheElement = 0 ;
var rightElement = "";
var leftElement = "";
var conteneurElement = "";

function rollRight() {
    var thumb = document.getElementById(conteneurElement);
    if (thumb) {
        thumb.scrollTop+=72;
        initFleches();
    }
}

function rollLeft() {
    var thumb = document.getElementById(conteneurElement);
    if (thumb) {
        thumb.scrollTop-=72;
        initFleches();
    }
}

function initFleches() {
    var navRight = getElement(rightElement, true, "") ;
    var navLeft = getElement(leftElement, true, "") ;

    var thumb = document.getElementById(conteneurElement);
    if (thumb) {
        var scrollTopElement = thumb.scrollTop;
        if (widthTheElement <= scrollTopElement) 
        {
            if (navLeft) {
                navLeft.style.visibility = "visible";
            }
            if (navRight) {
                navRight.style.visibility = "hidden";
            }
        }
        if (scrollTopElement == 0) 
        {
            if (navRight) {
                navRight.style.visibility = "visible";
            }
            if (navLeft) {
                navLeft.style.visibility = "hidden";
            }
        }
    }
}

function initRoll(_widthTheElement, _conteneurElement, _rightElement, _leftElement) {
    widthTheElement = _widthTheElement;
    conteneurElement = _conteneurElement;
    rightElement = _rightElement;
    leftElement = _leftElement;
    initFleches();
}