This is VT100.BUG

      Known Bugs & Problems

      DELETE LINE, ANY SCROLLING OR PAGING COMMAND, REVERSE
   VIDEO.

      EDT uses SET SCROLL to delete lines, by setting the
   scrolling region to the line you are on down to the bottom
   of the screen, then it sends a new line from the file to the
   bottom, and finally it resets the scrolling region to what
   it was.  The effect is to push the unwanted line off the
   screen.  I'm not sure how to do this on the Kaypro, since
   the program doesn't know what line you are on.

      To get around this, you can use control-R or control-W to
   repaint the screen each time you delete a line.

      SCROLLING with the arrow keys down past where a scroll is
   required will not insert a new line properly.  Scrolling
   upwards works, but two extra lines fall down into the
   message region.

      Again, you can repaint the screen to get around this.

      Selected regions are not highlighted, because I have an
   older KAYPRO II which does not support graphics.