But destructors should not be abstract. Would have been nice to have a compiler warning on that one. Line put on screen didn't get put in list of displayed lines. List object was designed for pointer objects, and assumed NULL could never be put in list. Using it for int objects, where value 0 was legal and occurred.
Screen just keeps dumping blank lines.
Had prototyped it with a simple global. Lines not displaying right when moving just off screen. This was causing storage to get trashed. Sorting was done on an illegal field. The field counter should have been wrapped to 0 when it reached the maximum, but was incremented instead.