Hactar editor can be used for almost any SGF editing purposes, including to record games, create problems or comment games.
ModesEditor is always in one of modes: View , Record , Markup , Setup or Scoring.
Icons in edit window:
Delete move. Deletes last visible played move.
Undo edit. Undo last change.
Insert Move or Add Variation?
When in middle to already recorded moves, it is possible to select between two actions when adding move: add variations or insert move .
When variation is added, new move is put into a new variation. This way existing recoding of game is not modified.
Inserting move can be used for example to add move that was forgotten when recordign the game.