Using ctrlSetStructuredText on with structured text *edits* this structured text object.
For example on a RscStructuredText control:
private _text = "abcd"; private _parsedText = parseText _text; _myControl ctrlSetStructuredText _parsedText; // will change _parsedText value _myControl ctrlSetStructuredText parseText _text // circumvents the issue
Thanks to @Dscha for finding it out.