fRanges= null; // mark for recomputation
    for (Iterator regions= fChangeRegions.iterator(); regions.hasNext();) {
      ChangeRegion region= (ChangeRegion) regions.next();
      region.clearDiff();
      for (int i= 0; i < hunks.length; i++) {
        Hunk hunk= hunks[i];
        region.adjustTo(hunk);
      }
    }
  }