function popup_window(url,name,win_width,win_height)
{
	pos_horizon = ((screen.width/2)-(win_width/2));
	pos_vertical = ((screen.height/2)-(win_height/2));
	window.open(url,name,"width="+win_width+",height="+win_height+",top="+pos_vertical+",left="+pos_horizon);
}