app.js

function dbg(o)
{
  Ti.API.info(o);
}
var win = Ti.UI.createWindow({backgroundColor: '#444'});

var btnProperties = {
    backgroundImage: 'enabled.png',
    backgroundDisabledImage: 'disabled.png',
    width: 70,
    height: 13,
  };
var btn1 = Ti.UI.createButton(btnProperties);
var btn2 = Ti.UI.createButton(btnProperties);

var controlBtn = Ti.UI.createButton(
  {
    title: 'Toggle',
    width: 100,
    height: 30,
    top: 10
  });
controlBtn.addEventListener('click', function()
  {
    try
    {
      dbg('toggling');
      dbg('is enabled '+btn1.enabled);
      btn1.enabled = !btn1.enabled;
      btn2.enabled = !btn2.enabled;
      dbg('became enabled '+btn1.enabled);
      win.setToolbar(null, {animated: false});
      setTimeout(function()
        {
          dbg('setting toolbar');
          win.setToolbar([btn1], {animated: false});
          dbg('set toolbar');
        }, 1000);
    }
    catch (err)
    {
      dbg('[ERROR!!!]'+err.message);
    }
  });

win.add(controlBtn);

//win.open();

win.add(btn2);
win.setToolbar([btn1]);

var tabGroup = Titanium.UI.createTabGroup();
var tab = Titanium.UI.createTab(
  {
    title: 'Test tab',
    window: win
  });
tabGroup.addTab(tab);

tabGroup.open();