var workingThreads = 0;

function startWorking(turnOffScreen) {
    workingThreads = workingThreads + 1;
    if (turnOffScreen) {
        $("#workingBox").css("height", $(document).attr("height"));   
        $("#workingBox").removeClass("hidden");
    }

    var scrollPos = document.documentElement.scrollTop || window.pageYOffset || 0;
    var clientHeight = window.innerHeight || document.documentElement.clientHeight || 0;
    var boxHeight = $("#workingMessage").height();
   
    var top = scrollPos + clientHeight - boxHeight - 10;

    $("#workingMessage").css("top", top);
    $("#workingMessage").removeClass("hidden");   
}

function stopWorking() {
    $("#workingBox").addClass("hidden");
    $("#workingMessage").addClass("hidden");

    workingThreads = 0;
}