Sample code for Richard Olenick in answer to http://developer.appcelerator.com/question/159878/trying-to-switch-windows-with-use-of-a-button-click#comment-195523 assumes all these files are in Resources/

app.js

var Login = require('loginScreen');
var loginPage = new Login();

loginPage.open();

homeScreen.js

function Home(){
 
    var win = Titanium.UI.createWindow({
        title: "Label View",
        backgroundColor: 'orange',
        exitOnClose: true,
        layout: 'vertical'
    });
 
    var AvailableJobsButton = Titanium.UI.createButton({
        title: "Available Jobs",
        top: "10%",
        height: "10%",
        width:"100%",
        font:{fontSize: "32"},
        id: "AvailableJobs", //custom property
 
    });
 
    var CurrentJobsButton = Titanium.UI.createButton({
        title: "Current Jobs",
        top: "40%",
        height: "10%",
        width:"100%",
        font:{fontSize: "32"},
        id: "CurrentJobs", //custom property
 
    });
 
    var CompletedJobsButton = Titanium.UI.createButton({
        title: "Completed Jobs",
        top: "70%",
        height: "10%",
        width:"100%",
        font:{fontSize: "32"},
        id: "CompletedJobs", //custom property
 
    });
 
    AvailableJobsButton.addEventListener("click", function(e){
        alert(e.source.id + " fired a " + e.type + " event");
    });
 
    CurrentJobsButton.addEventListener("click", function(e){
        alert(e.source.id + " fired a " + e.type + " event");
    });
 
    CompletedJobsButton.addEventListener("click", function(e){
        alert(e.source.id + " fired a " + e.type + " event");
    });
 
 
    win.add(AvailableJobsButton);
    win.add(CurrentJobsButton);
    win.add(CompletedJobsButton);
 
    return win;
}
 
module.exports = Home;

loginScreen.js

/**
 * @author Ricky
 */
function Login(){
 
    var win = Titanium.UI.createWindow({
        title: "Login Screen",
        backgroundColor: "orange",
        exitOnClose: true
    });
     
    var ClutchInspectLabel = Titanium.UI.createLabel({
        text: "ClutchInspect",
        color: "black",
        top: "10%",
        font: {fontSize: "42"}  
    });
     
    var LoginButton = Titanium.UI.createButton({
        title: "LOGIN",
        top: "80%",
        height: "10%",
        width:"45%",
        font:{fontSize: "24"},
        id: "Login", //custom property
     
    });
     
    var UserNameBox = Titanium.UI.createTextArea({
        borderWidth: 2,
        borderColor: '#bbb',
        borderRadius: 5,
        color: '#888',
        font: {fontSize:20, fontWeight:'bold'},
        keyboardType: Ti.UI.KEYBOARD_DEFAULT,
        returnKeyType: Ti.UI.RETURNKEY_NEXT,
        textAlign: 'left',
        value: '',
        top: "45%",
        left: "25%",
        width: 300, height : 50
    });
     
    var PasswordBox = Titanium.UI.createTextArea({
        borderWidth: 2,
        borderColor: '#bbb',
        borderRadius: 5,
        color: '#888',
        font: {fontSize:20, fontWeight:'bold'},
        keyboardType: Ti.UI.KEYBOARD_DEFAULT,
        returnKeyType: Ti.UI.RETURNKEY_DONE,
        passwordMask: 'true',
        textAlign: 'left',
        value: '',
        top: "55%",
        left: "25%",
        width: 300, height : 50,
    });
     
     
    var InputPassword = Titanium.UI.createTextField({
        id:'InputPassword',
        hintText:Ti.Locale.getString('Password'),
        passwordMask:true,
        className:'DefaultPasswordField',
    });
     
    var UserNameLabel = Titanium.UI.createLabel({
        text:"Username:",
        top: "45%",
        left: 0,
        textAlign: "center",
        font:{fontSize: "24"},
        color: "black",
        backgroundColor: "orange"
     
    });
     
    var PasswordLabel = Titanium.UI.createLabel({
        text:"Password:",
        top: "55%",
        left: 0,
        textAlign: "center",
        font:{fontSize: "24"},
        color: "black",
        backgroundColor: "orange"
    });
     

     
    
     
    LoginButton.addEventListener("click", function() {
        var Home = require('/homeScreen');
        var homePage = new Home();
        homePage.open();    
    });
     
     
    //win.add(InputPassword);
    win.add(UserNameBox);
    win.add(PasswordBox);
    win.add(UserNameLabel);
    win.add(PasswordLabel);
    win.add(LoginButton);
    win.add(ClutchInspectLabel);

 
    return win;
}
module.exports = Login;