private @Nullable Splitter findRootSplitter() {
    Splitter splitter = getParentSplitter(myWrapperPanel);
    while (splitter != null) {
      Splitter parentSplitter = getParentSplitter(getSplitterParent(splitter));
      if (parentSplitter == null) break;
      splitter = parentSplitter;
    }
    return splitter;
  }
private @Nullable Splitter findRootSplitter()