'This is a feature that comes only with older versions of GNOME. The screenshot you are looking at is of an older version of GNOME Shell. In versions of GNOME prior to 3.8, there was a category selector on the right side as your screenshot shows. In GNOME 3.8, the category filter was removed and applications can now be launched using either a "Frequent" or "All" filter.' (Sneetsher from Askubuntu)
Here the link of the same thread I started in Askubuntu:
http://askubuntu.com/questions/46939...ctivities-view