Appcelerator switch windows

I have a main window (app.js) and two sub-windows (login.js and signUp.js)

Here is my app.js

var login=Titanium.UI.createWindow({
    url:'wins/login.js',
    title:'Login',
        backgroundColor:'#CCC',
        navBarHidden:true
});
var signUp=Titanium.UI.createWindow({
        url:'wins/signUp.js',
    title:'Sign-up',
        backgroundColor:'#CCC',
        navBarHidden:true
});

login.open({fullscreen:true});

Now I want to open signUp.js from with login.js. Is there any way to do this? I've tried googling and reading over the documentation开发者_高级运维 to no avail.

---

just typed this up, not perfect, but this is the general idea.

// create buttons on main window
var loginBtn = Titanium.UI.createButton({
    title : 'LOGIN'
});
var signUpBtn = Titanium.UI.createButton({
    title : 'SIGN UP'
});

// add to window
mainWindow.add(loginBtn);
mainWindow.add(signUpBtn);

// associate click events
loginBtn.addEventListener('click', function() {
    Ti.API.log('loginBtn button clicked, show window');
    login.open();
});

signUpBtn.addEventListener('click', function() {
    Ti.API.log('signUpBtn button clicked, show window');
    signUp.open();
});