// ---- swapButton ----------------------------------------------------------------------------- //
function swapButton(x) {
	var btn = document.getElementById(x);
	var src = btn.src.split('/').pop();
	var name = src.split('_')[0];
	var state = src.split('_')[1];
	var newbtn = (state == 'on.gif') ? name+'_off.gif' : name+'_on.gif';
	btn.src = "images/"+newbtn;
    return;
}