With the 3D section feature, the opening conditions of the doors/windows are also taken into account and displayed in the sections. If the box is not checked, the doors/windows are considered closed in sections, regardless of their opening status.
Location of 3D Section Feature
You can access the 3D section feature from the types tab of the door/window settings dialog .
Section with 3D section feature is unchecked
Section with 3D section feature is checked