Hello I have been using the gumball for scaling for years and it always scales in two directions when I pull on the handles.
Nevertheless, sometimes it scales in 1D. I am interested in having it scale 1D all the time. I have referred to this link: http://docs.mcneel.com/rhino/5/help/en-us/commands/gumball.htm
Thank you for your prompt reply; however, it does not seem to scale in one direction for me. A curve always scales equally in both directions. See attached as it shows exactly what I mean.