var forcedRefresh = true;
/* The forcedRefresh variable specifies how the function should 
	 behave if the user clicks a link to open a window after it has 
	 already been opened. If set to true, the window will refresh 
	 with the address specified. If set to false, the window will 
	 simply gain the focus and not refresh its contents. */

var alreadyopen = new Array();
var newwin = new Array();

function openCenteredWindow(theURL, winName, features, w, h){
  var winl = parseInt((screen.width - w - 10) / 2);
  var wint = parseInt((screen.height - h - 29) / 2);
  openWindow(theURL, winName, features + ',height=' + h + ',width=' + w + ',top=' + wint + ',left=' + winl);
}

function openWindow(theURL, winName, features){
  if(forcedRefresh == false && alreadyopen[winName] && !newwin[winName].closed){
    newwin[winName].focus();
  }
  else{
    alreadyopen[winName] = 1;	
    newwin[winName] = window.open(theURL, winName, features);
    newwin[winName].focus();
  }
}