Android does not have concept of navigational Window but it do have action Bar which only works for 3.0+ android version so you have to keep that in mind before using that.Other than that you can fake the navigation-window by adding a view to window for android 3.0-
var win=Ti.UI.createWindow();
if(Ti.Platform.osname==='android'){
var view=Ti.UI.createView({
backgroundColor:'black',
height:'40dp',
top:'0dp',
width:Ti.UI.FILL
})
}
win.add(view);
win.open();
Thanks