img1on = new Image(); img1on.src = "images/arrowon_l.gif";
img1off = new Image(); img1off.src = "images/arrowoff_l.gif";
img2on = new Image(); img2on.src = "images/arrowon_r.gif";
img2off = new Image(); img2off.src = "images/arrowoff_r.gif";

function imgAct(imgName) { document[imgName].src = eval(imgName + "on.src"); }
function imgInact(imgName) { document[imgName].src = eval(imgName + "off.src"); }