message: Use the rawDisplayName for the user provider completion
  to make sure that the length of text in the decoration (See <Pill>) is equal to the length of text in the completion (underlying text range that the Entity covers).
diff: @@ -54,7 +54,9 @@ export default class UserProvider extends AutocompleteProvider {
  completions = this.matcher.match(command[0]).map((user) => {
  const displayName = (user.name || user.userId || '').replace(' (IRC)', ''); // FIXME when groups are done
  return {
  - completion: displayName,
  + // Length of completion should equal length of text in decorator. draft-js
  + // relies on the length of the entity === length of the text in the decoration.
  + completion: user.rawDisplayName,
  suffix: range.start === 0 ? ': ' : ' ',
  href: 'https://matrix.to/#/' + user.userId,
  component: (
  