Yesterday I had to stop trying in my laptop. Inventor hogs its little memory maybe helped by the stupid AVG who refuses to uninstall, says that is desactivated (!) but checks every single file I read, write continuously. Enough!
I got answers in their forum but then I also run across this.
With my PCs and laptop I find App Inventor a little bit clunky (have to admit that with my daughters Win 7 laptop it was somewhat better). Given this and the above (limitations) I am considering I could resort to RFOBasic!.