function openMaster(){
var sw= screen.availWidth/2;
var sh = screen.availHeight/2;
//these numbers are based on the size of the window opening.
//wh is the height
//ww is the width
var wh = 450/2;
var ww = 570/2;
xpos=  sw - ww;
ypos = sh - wh;
var features = "height=450,width=570,left=" + xpos + ",top=" + ypos;
new_window = window.open('master.html', '', features);
}

function openGuest1(){
var sw= screen.availWidth/2;
var sh = screen.availHeight/2;
//these numbers are based on the size of the window opening.
//wh is the height
//ww is the width
var wh = 450/2;
var ww = 570/2;
xpos=  sw - ww;
ypos = sh - wh;
var features = "height=450,width=570,left=" + xpos + ",top=" + ypos;
new_window = window.open('guest1.html', '', features);
}

function openGuest2(){
var sw= screen.availWidth/2;
var sh = screen.availHeight/2;
//these numbers are based on the size of the window opening.
//wh is the height
//ww is the width
var wh = 320/2;
var ww = 570/2;
xpos=  sw - ww;
ypos = sh - wh;
var features = "height=320,width=570,left=" + xpos + ",top=" + ypos;
new_window = window.open('guest2.html', '', features);
}