var win = null;
function NewWindow(mypage,myname,w,h,features){

if (w==''){w='638';}
if (h==''){h='450';}

LeftPosition = (screen.width) ? (screen.width-w)/2 : 0;
TopPosition = (screen.height) ? (screen.height-h)/2 : 0;

settings =
'height='+h+',width='+w+',top='+TopPosition+',left='+LeftPosition+','+features

win = window.open(mypage,myname,settings)
if(win.window.focus){win.window.focus();}
}