I know that styles have an attribute to allow/avoid changes in the text in which they are applied:
SCI_STYLESETCHANGEABLE(int style, bool changeable)
However, the documentation says "This is an experimental and incompletely implemented style attribute.", which seems it is not "production-ready"
I think there is another alternative, using "Indicators":
To protect a range of text, we could apply an specific indicator to it and in keydown event detect "del" & "backspace". If the character that follows current position (caret position) in "del" case or that precedes current position in "backspace" case has this indicator, then we must cancel the event and do not erase the text.
Which of this 2 alternatives is better? There is another better way?
Note: ScintillaNet is based on Scintilla and I assume that the extensive documentation of the last one is valid for both.