var timeOn = null;
function show(z) { hall(); toff(); eval("document.getElementById('drop" + z + "').style.visibility = 'visible'"); }
function hide(z) { eval("document.getElementById('drop" + z + "').style.visibility = 'hidden'"); }
function hall() { for (var i = 1; i <= 5; i++) hide(i); }
function ton(z) { timeOn = setTimeout("hide(" + z + ")", 500); }
function toff() { clearTimeout(timeOn); }