var old;
var memold;
if(document.layers)
{ window.captureEvents(Event.MOUSEUP); window.onmouseup=do_out;} else { document.onmouseup=do_out;}
function show_layer(x)
{if(document.getElementById) document.getElementById(x).style.visibility="visible"; else if(document.layers) document.layers[x].visibility="show"; else document.all[x].style.visibility="visible";}
function hide_layer(x)
{if(document.getElementById) document.getElementById(x).style.visibility="hidden"; else if(document.layers) document.layers[x].visibility="hide"; else document.all[x].style.visibility="hidden";}
function do_menu(x)
{if(old!=x){show_layer(x);old=x;} else old="";}
function do_check(x)
{if(old && old!=x){hide_layer(old);show_layer(x);old=x;}else if(!old){do_menu(x);}}
function do_out()
{if(old) hide_layer(old);memold="";old="";}