I was watching the YouTube video Top 5 Features of Ice Cream Sandwich with Mono for Android 4.0, and I tried to follow along with the part about creating tabbed applications with the action bar. However, I cannot use the code from the video; the ActionBar property doesn't exist, neither does the ActionBarNavigationMode enum, or the Fragment class. I've double checked this in the assembly browser. I've re-downloaded the Mono for Android installer to make sure I have the most recent version, but when I look at the references, the Mono.Android version is 18.104.22.168. How do I get access to the new features in Android 4.x?