function diashow_popup(){
LeftPosition = (screen.width) ? (screen.width-600)/2 : 0;
TopPosition = (screen.height) ? (screen.height-400)/2 : 0;
settings =
'height=400,width=600,top='+TopPosition+',left='+LeftPosition+',scrollbars=auto,resizable=no'
open("diashow.html","diashow",settings)
}