How would you create an extension that replaces each character in a selection with a special character, perhaps a ▬? Doing so would redact the selected text, while maintaining the same length. Spaces could be replaced as well so that it isn’t necessary to treat them separately.
Examples:
Redact the word Popclip from this sentence.
Redact the word ▬ ▬ ▬ ▬ ▬ ▬ ▬ from this sentence.
Redact the next word from this sentence.
Redact the next ▬ ▬ ▬ ▬ from this sentence.
Redact the next three words from this sentence.
Redact the next ▬ ▬ ▬ ▬ ▬ ▬ ▬ ▬ ▬ ▬ ▬ ▬ ▬ ▬ ▬ ▬ this sentence.