The Drawing Settings allow you to control how Codesign responds while you are sketching:
Create items automatically is used to control if items are created as soon as you draw a closed shape.
Snap to orthogonals provides the ability for your sketched strokes to snap to the vertical and horizontals - creating perfect 90 degree corners.
Snap to elements means that strokes will align themselves (either parallel or perpendicular) to existing elements and strokes.