@Nullable
 public TextRange performReplace(
     final FindResult occurrence, final String replacement, final Editor editor) {
   if (myReplaceDenied
       || !ReadonlyStatusHandler.ensureDocumentWritable(editor.getProject(), editor.getDocument()))
     return null;
   FindModel findModel = mySearchResults.getFindModel();
   TextRange result =
       FindUtil.doReplace(
           editor.getProject(),
           editor.getDocument(),
           findModel,
           new FindResultImpl(occurrence.getStartOffset(), occurrence.getEndOffset()),
           replacement,
           true,
           new ArrayList<Pair<TextRange, String>>());
   myLivePreview.inSmartUpdate();
   mySearchResults.updateThreadSafe(findModel, true, result, mySearchResults.getStamp());
   return result;
 }
 private void smartUpdate() {
   myLivePreview.inSmartUpdate();
   updateInBackground(mySearchResults.getFindModel(), false);
 }