At the right hand side of the editor window is an optional area which provides one of a range of useful lists of parts of the session. It is not shown by default when first starting using Ardour. The Editor list can be hidden or shown using View > Show Editor List. The very right-hand side of the list gives a selection of tabs which are used to choose the list to view. The left-hand border of the list can be dragged to vary the width of the list.