var handlePrevButtonState = function(type, args) {

    var enabling = args[0];
    var leftImage = args[1];
    if(enabling) {
        leftImage.src = "images/up-enabled.gif";    
    } else {
        leftImage.src = "images/up-disabled.gif";    
    }
    
};

var handleNextButtonState = function(type, args) {

    var enabling = args[0];
    var rightImage = args[1];
    
    if(enabling) {
        rightImage.src = "images/down-enabled.gif";
    } else {
        rightImage.src = "images/down-disabled.gif";
    }
    
};