CAD Q's
The line and arc tools are flex-track.
Start a new "Test" drawing and place a piece of track from the Library, such as a N_ATLAS_CRW's F30 (Atlas part number A2503)
Click on the "Draw Lines Tool" button on the left side of the screen.
Locate and click on the "Project Line" button.
Click on one of the ends of the Library part you added to the drawing and hold down the left mouse button.
Drag (move) the mouse a little ways away from the part and see if the line draws.
Curves work the same way but you should play with the different types to see how they work.