var popWin = null;

function popup(mylink, name,w,h)
{
//var h = 400;
//var w = 600;
if (popWin && !popWin.closed)
{
//alert('Window Open');
popWin.close();
}

winprops = 'height='+h+',width='+w+',scrollbars=yes,resizable,toolbars=yes';
popWin = window.open(mylink, name,winprops);
popWin.focus();
//popWin.document.close();
return false;
}