Yes, I made it this way on purpose because I don't know the value of the parameter. In the viewer, you can change its value easily and consistent, but in the script editor adding a field for the parameter's value could be too confusing. At least, I don't know how to solve it gracefully :)
SQ-1026 This may be by design, but I can still execute the script from the viewer, perhaps in NEXT release we could solve this. Not a show stopper IMO.Stephen