Drag a point from a corner of the square to produce a line. You can draw four lines, colored red, blue, green and magenta. You can save lines. You can drag the four points , , and , which are reflected across all lines. You can also save mapped points. Use Alt+Click (Cmd+Click) to add points in the square.
Reflections are equivalent to paper folding.
To show the validity of Huzita's sixth axiom, draw two lines using the red line.