function openPopup( popup_name, popup_url, popup_width, popup_height, popup_scrollbars, popup_toolbar, popup_status) {
	popup_left = (screen.width)  ? (screen.width  - popup_width) / 2  : 0;
	popup_top  = (screen.height) ? (screen.height - popup_height) / 2 : 0;
	settings   = 'height='+popup_height+',width='+popup_width+',top='+popup_top+',left='+popup_left+',scrollbars='+popup_scrollbars+',toolbar='+popup_toolbar+',status='+popup_status+',resizable=yes';
	win = window.open(popup_url,popup_name,settings);
	if(win.window.focus)
		win.window.focus();
}

function showImage(buttonID) {
    document.getElementById("image_" + buttonID).src = highlightButton[buttonID].src;
}

function hideImage(buttonID) {
    document.getElementById("image_" + buttonID).src = normalButton[buttonID].src;
}