var tmax = 19;
var nav1 = 1;
var shifting = 0;

function img(id, src, tags) {
    if (typeof(tags) == "undefined") tags = "";
    return "<img id='" + id + "' src='" + src + "' " + tags + ">";
    }

function rollover(id, over, out) {
    var tags = "onMouseOver='" + over + "'";
    tags += " onMouseOut='" + out + "'";
    return img(id, "tb-" + id + ".jpg", tags);
    }

function a(href, x) {
    return '<a href="' + href + '">' + x + '</a>';
    }

function show(o) {
    tabula.src = o.src.replace("ico", "img");
    }

function mknav() {
    var s = rollover("prev", "shifting = 1; shiftit(\"<\")", "shifting = 0");
    s += "<div id='ribbon'>";
    for (var i = 1; i <= tmax; i++) {
        s += "<img id='nav' src='" + i + ".ico.jpg' onMouseOver='show(this)'>";
        // s += i;
        }
    s += "</div>";
    s += rollover("next", "shifting = 1; shiftit(\">\")", "shifting = 0");
    s += a("?", img("exp", "tb-exp.jpg"));
    document.writeln(s);
    }

function shiftit(dir) {
    if (!shifting) return;

    if (dir == ">") {
        if (nav1 == (imax - tmax + 1)) return;
        nav1++;
        }
    else {
        if (nav1 == 1) return;
        nav1--;
        }

    for (var i = 0; i < tmax; i++) {
        document.images[i+3].src = (i + nav1) + ".ico.jpg";
        }
    setTimeout("shiftit('" + dir + "')", 250);
    }

function raise(o) {
    o.src = o.src.replace(/normal/, "raised");
    }
function normal(o) {
    o.src = o.src.replace(/raised/, "normal");
    }