This has been asked several times in the past and nobody has answered it. It's really annoying as I love Producteev, and have no idea why the owners don't plug it more as nobody knows about it! I found out about Producteev from comments in an article about some other application.
Anyway, I am plugging the program to colleagues and now I have to tell them, err whoops this one thing that could be so useful doesn't work unless you're online on the web. Or unless the file is a pdf.
I have a tablet (android) and a mobile phone (android) and both get the same error message when I try to open up an attachment (such as a doc file or excel). So annoying! As I want the experience for the people I refer to be seamless and trouble-free...but alas.
I hope I get an answer this year! Hopefully in next week or so! Hope, pray!