The latest support library (r18) brings ActionBar support all the way back to Android 2.1 (API level 7) but the invalidateOptionsMenu function is only supported in API 11 and higher. If you want to hide an icon or change the look of the menu, your app needs to refresh the options menu.
Call supportInvalidateOptionsMenu() within your ActionBarActivity class or within your Fragment by calling getActivity().supportInvalidateOptionsMenu(). This function allows you to invalidate the options menu. More information about support library functionality for the ActionBarActivity can be found here:
I’ve implemented the new ActionBarActivity on my current project and have been very happy with the performance and functionality. It was an easy transition from using ActionBarSherlock. The biggest difference is with some of the support library functions and with the theme. Luckily, the ActionBar style generator has already been updated to use the new AppCompat theme!