After much struggling with trying to make Java Swing's JTable component bend to my will, I concluded that 95% was the high watermark, so completely rewrote it from the ground up. The new version of the DataSheet editor is nicer to use, and has been summarily tested with a couple of data entry scenarios, but for all I know is still buggier than a cheap tropical motel. It will be cleaned up over the next few months, however, since I intend to use it for my own work.