var current_image = "";
var image_base = "";
var over, out;
var loaded = 0;

function loadImages () {
    var images = loadImages.arguments;
    
    over = new Array(images.length);
    out  = new Array(images.length);
    
    for (i=0; i<images.length; i++) {
        over[ images[i] ]     = new Image;
        over[ images[i] ].src = image_base + images[i] + '-lit.gif';
        out[ images[i] ]      = new Image;
        out[ images[i] ].src  = image_base + images[i] + '.gif';
    }

    loaded++;
}

function swap (which, lit) {
    if (!loaded)
        return;

    if (which != current_image)
        document.images[which].src = lit ? over[which].src : out[which].src;
}

function set_current (which) {
    if (!loaded)
        return;

    if (current_image != "" && which != current_image)
        document.images[current_image].src = out[current_image].src;
    current_image = which;
}