@Override
    protected JComponent createCenterPanel() {
      final JComponent tree = super.createCenterPanel();

      myCommitMessagePanel = new CommitMessage(myProject);
      myCommitMessagePanel.setCommitMessage("Initial commit");

      Splitter splitter = new Splitter(true);
      splitter.setHonorComponentsMinimumSize(true);
      splitter.setFirstComponent(tree);
      splitter.setSecondComponent(myCommitMessagePanel);
      splitter.setProportion(0.7f);

      return splitter;
    }
 @NotNull
 public String getCommitMessage() {
   return myCommitMessagePanel.getComment();
 }