Is there a Mac OS X version of Sketchpad?
Yes; as of Sketchpad version 4.03 (August 2002), Sketchpad now features native support for Mac OS X. Determine which version of Sketchpad you have by looking at the title window during program startup or when you choose “About Sketchpad…” from the Apple or Help menu. If you have an older version of Sketchpad 4, you can update to the latest version here.