function switch_visible(el) {
    el = document.getElementById(el);
    swith_visible_c(el);
}
function swith_visible_c(el) {
    if (el.style.visibility=="hidden") {
        el.style.visibility="visible";
        el.style.display="block";
    } else {
        el.style.visibility="hidden";
        el.style.display="none";
    }
}
function setInvisible(el) {
	el = document.getElementById(el);
        el.style.visibility="hidden";
        el.style.display="none";
}
function setVisible(el) {
	el = document.getElementById(el);
        el.style.visibility="visible";
        el.style.display="block";
}