var container;
var positionX = 0;
var grenze = 0;
var stopAnimation = false;

function startSlideshow(thisContainer) {

    container = document.getElementById(thisContainer);
    var aktiv = window.setInterval("Farbe()", 33);

    grenze = container.style.width.split("px")
    grenze = grenze[0] / -3;

}

function Farbe() {

    if(stopAnimation) return false;
    else positionX -= 1;

   if(positionX <= grenze) positionX = 0;

   container.style.left = positionX + "px";

}