var win=null;

function NewWindow(mypage,myname,w,h,scroll){

LeftPosition=(screen.availWidth)?(screen.availWidth-w)/2:10;
TopPosition=(screen.availHeight)?(screen.availHeight-h)/2:10;
settings='width='+w+',height='+h+',top='+TopPosition+',left='+LeftPosition+',scrollbars='+scroll+',location=no,directories=no,status=no,menubar=no,toolbar=no,resizable=no';
win=window.open(mypage,myname,settings);
if(win.focus){
win.focus();
}

}

function CloseNewWin(){
if(win!=null && win.open)win.close()
}

window.onfocus=CloseNewWin;