TrvActionShowSpecialCharacters is the action for "Non-printing Characters" command.
TrvActionShowSpecialCharacters = class(TrvAction)
The action shows/hides:
•marks for non-printing characters (spaces, non breaking spaces, tabs, soft hyphens, paragraphs separators, line separators) and placeholders of floating items;
•(if ShowCheckpoints = True) checkpoints.
The set of non-printing characters to display is defined in RVVisibleSpecialCharacters global variable (declared in RVStyle.pas).
The action includes/excludes rvoShowSpecialCharacters, rvoShowHiddenText, rvoShowCheckpoints from TCustomRichViewEdit.Options property and reformats TCustomRichViewEdit.
This action assumes that these options are included and excluded from Options together. Make sure that it is true for the initial state of editors in your application.