Contacts are not properly greyed out on older Android versions
When sharing a forum, contacts who already belong to the forum are greyed out in the contact chooser. On newer Android versions (tested on Android 5.1), the avatar, contact name and checkbox all have a light grey fade. On older versions (tested on Android 2.3.3), the avatar has a dark grey fade, the contact name does not appear to be faded, and the checkbox has a light grey fade. It's not obvious that the item is meant to be disabled - it looks like the avatar is just discoloured.