// preload images for navigation
//
function loadImages() {
    // ignore browsers without image array
    if (document.images) { 
        // create on and off state objects in theImages for each member of theButtons
        for(i = 0; i < theButtons.length; i++) {
            theImages[theButtons[i]+"_on"] = new Image();
            theImages[theButtons[i]+"_on"].src = theImagesPath + theButtons[i] + "_btn_on.gif";
            theImages[theButtons[i]+"_off"] = new Image();
            theImages[theButtons[i]+"_off"].src = theImagesPath + theButtons[i] + "_btn_off.gif";
        }
    }
}

function changeImage(imgName, state) {
            // ignore browsers without image array
            if (document.images && theImages[imgName +"_" + state]) {
                document.images[imgName].src = theImages[imgName +"_" + state].src;
}    
}