The right-click menu show possible actions depending on what has focus on the Plan.
At the bottom of the plan are Coordinates and Hints. The coordinates section shows the current mouse location in world coordinates. An elevation is also shown if a TIN Surface has been loaded. Deluge results are also given if data is available.
The hints section details the typical actions available to you depending on the mouse position and what item has focus on the Plan.
The center divider can be moved by dragging it with the mouse.