From Flux Developer Wiki

CROSS SECTION EDITOR:

The 2-D cross section window and commands allow you to draw a cross section that will be used to model one of the ExtrudedShapes. The 2-D cross section consists a series of connected lines. You want to use as few lines as possible to reduce the polygon count. A floating tool bar containing most of the options will popup when a cross section window is created.

The cross section menu consists of four radio buttons, and four commands. The radio buttons determine the current cross section editor mode of operation. The four radio buttons are "Add Point", "Add Point At End", "Move Point", and "Delete Point".

Add Point: When you click on the Window, you will Add a Point to the nearest segment.

Add Point at End: When you click on the Window, you will Add a Point to the nearest EndPoint of the chain

Move Point: When you Click and Drag, you will be moving the nearest point as you drag.

Delete: When you Click, you delete the nearest point..

The other four Icons are:

Close Cross Section: If the Cross Section is not already closed, it will add a point to close the Cross Section..

Apply and Exit Window: Applies the Cross Section to the 3D Shape, and closes the Window.

Toggle Show Grid:

Toggle Snap To Grid:

You can also access these options clicking and holding the right mouse button while in the cross section creation window. There are several other command specific to the Cross Section that can be found in the Right Mouse Popup Menu:

Apply will apply the Cross Section to the 3D Shape, but it keeps the 2D editor open.

Abort will close the Cross Section Editor, and NOT save the shape.

Mirror/Scale/Rot will take you to the following dialog to control mirror, scale, rotate, and translate.

The Edit Grid Options Command will bring up the typical Grid Options Dialog.

The Copy and Paste Cross Section Command will Copy and Paste the Cross Section to and from the Cross Section Clipboard.  The Cross Section will get copied to or from the Cross Section Editor, not the 3D Shape.

Pick New Origin will let you pick a new center, and it will move all the points accordingly.

Rotate 90 will rotate all the points 90 degrees.

Normalize Width and Height will scale the width or Height so the total span of the width or Height is one.

Enable Auto CCW will turn on the mode where it will automatically order the points so that you have a Counter Clockwise Cross Section.

Reverse Order will only be available if Auto CCW is OFF.  If the Auto CCW is off, then you can control the order, and this command lets you reverse the order of the points.