function centerForm(win)
{
var aform = document.getElementById(win);
var w = screen.width - parseInt(aform.style.width);
var ww = w/2;
aform.style.left = ww;
}
function hideForm(win)
{
var aform = document.getElementById(win);
aform.style.visibility = 'hidden';
}
function showForm(win)
{
var aform = document.getElementById(win);
aform.style.visibility = 'visible';
}