I ran into Mark Murphy in Bethlehem PA who wrote another book on Android App programming. We discussed the App Inventor is some detail and both agreed that to implement a more sophisticated app, you need to stay with the java/xml type programming that we are currently doing. Although this may be something to look into in the future, there are many limitations with App inventor right now. Right now app inventor is only meant to be a student aid to introduce new students on this technology. One example I found was that there isn’t a component to change the date or time. At least when I last checked. Then the idea might be to write you own block / module to give you that capability. There is a special language which the folks at MIT are currently using and right now I don’t think that’s open to the public.