Toggle Manipulator

The center of the main and most 1st level Pie menus toggles to open or close the Manipulator.

When the command icon has a black background color, the Manipulator will be opened. It can be placed in the 3D View and positioned a simple mouse click or by using other objects as reference.

When it is open already the command background is green color highlighted.

Selecting it then will close the Manipulator.