function TopLeft(Width, Height) {
  var winWidth, winHeight;
  winWidth = (screen.availwidth - Width)/2;
  winHeight = (screen.availheight  - Height)/2;
  var T =
  "top="    + winHeight + "," +
  "left="   + winWidth  + "," +
  "width="  + Width     + "," +
  "height=" + Height
  return T;
}


function AircraftPopup(URL) {
  var MyWindow = window.open(URL, 'MyWindow', TopLeft(620,494) + "status=yes,resizable=yes,scrollbars=yes");
  if(MyWindow) MyWindow.focus();
}

function OpenPopup(URL) {
  var winWidth, winHeight;
  winWidth = (screen.availwidth - 420)/2;
  winHeight = (screen.availheight  - 400)/2;
  var thistopleft;
  thistopleft = "top=" + winWidth + ",left=" + winHeight + ",";
  
  var MyWindow = window.open(URL, 'MyWindow', thistopleft + "width=420,height=400,status=yes,resizable=yes,scrollbars=Yes");
  if(MyWindow) MyWindow.focus();
}

function OpenPopupWidth(URL,width,height) {
  var MyWindow = window.open(URL, 'MyWindow', TopLeft(width,height) + ",status=yes,resizable=yes,scrollbars=yes");
  MyWindow.focus();
}