[AC-2975] Ti.UI.createWindow lost from scope in sub-context global reference

Code below shows how calling Ti.UI.createWindow from a global object method when the method is called from sub-context reference it produces no error, only returning undefined. Expected would be a throw error or a TiUIWindow object returned in line 10 of app.js. Wether it should or not, this code works on 1.6.3.

Titanium.UI.setBackgroundColor('#000');

var app = {
    windows: [],
    Window: function(id) {
        if (!this.windows[id]) {
            this.windows[id] = Ti.UI.createWindow({url: id + '.js'});
            Ti.API.log('created window: ' + JSON.stringify(this.windows[id]));
            this.windows[id].app = this;
        }
        this.windows[id].open();
        return this.windows[id];
    }
};

app.Window('win').open();

({
    init: function() {
        var button = Ti.UI.createButton({ bottom: 0, title: "open win2", width: '100%', height: '10%' });
        button.addEventListener('click', function(e) {
            Ti.UI.currentWindow.app.Window('win2');
        });

        Ti.UI.currentWindow.add(button);
    }
}).init();

Log when button is clicked: {noformat} [INFO] scopebug/1.0 (1.7.0.a41eefd...) [DEBUG] Analytics is enabled = YES [DEBUG] loading: /Users/jclark/Documents/Titanium Studio Workspace/scopebug/Resources/app.js, resource: Users/jclark/Documents/Titanium Studio Workspace/scopebug/Resources/app_js [INFO] created window: {"orientationModes":null,"url":"win.js"} [DEBUG] application booted in 32.694995 ms [DEBUG] loading: /Users/jclark/Documents/Titanium Studio Workspace/scopebug/Resources/win.js, resource: Users/jclark/Documents/Titanium Studio Workspace/scopebug/Resources/win_js [INFO] created window: undefined [WARN] Exception in event callback. { expressionBeginOffset = 391; expressionCaretOffset = 407; expressionEndOffset = 418; line = 10; message = "Result of expression 'this.windows[id]' [undefined] is not an object."; name = TypeError; sourceId = 116344464; sourceURL = "file://localhost/Users/jclark/Documents/Titanium%20Studio%20Workspace/scopebug/Resources/app.js"; } {noformat}