loaded=0;

function loadpix() {

b_str = new Image; b_str.src = '../images/str_menu.gif';
b_spacer = new Image; b_spacer.src = '../images/spacer.gif';

loaded=1;
}

function change(No, on) {
if (document.images['str'+No] && loaded) {
if (on) {
document.images['str'+No].src = b_str.src;
} else {
document.images['str'+No].src = b_spacer.src;
}
}
}