This week's book giveaway is in the Android forum. We're giving away four copies of Android Programming: The Big Nerd Ranch Guide and have Bill Phillips & Chris Stewart on-line! See this thread for details.
Yes, that's for opening a file, i guess i've misunderstood your question.
Are you asking how to implement those options, how to show the context menu or if it's possible to open the context menu of an external app (Astro I asume)?