New input with a token highlighted should replace the token

[benpackard]

1. Enter a string and tap return to tokenize it
2. Use back-delete to highlight the token
3. Type some characters

Expected: The new input replaces the existing token
Actual: The input is seemingly ignored, and the highlighted token is unaffected. When subsequently attempting to use the back-delete key again to remove the token, nothing happens until the number of deletions matches the number of invisible characters entered.