Program: 52773
Project: 52773
Buggy source:
public SimpleToolWindowPanel createToolWindowContent(final Project project){
  changeListPanel.registerChangeListPanel(this);
  changeListPanel.setProject(project);
  diffManager.registerDiffTool(commentsDiffTool);
  SimpleToolWindowPanel panel=new SimpleToolWindowPanel(true,true);
  ActionToolbar toolbar=createToolbar(project);
  toolbar.setTargetComponent(changeListPanel);
  panel.setToolbar(toolbar.getComponent());
  RepositoryChangesBrowser repositoryChangesBrowser=repositoryChangesBrowserProvider.get(project,changeListPanel);
  Splitter detailsSplitter=new Splitter(true,0.6f);
  detailsSplitter.setShowDividerControls(true);
  changeListPanel.setBorder(IdeBorderFactory.createBorder(SideBorder.TOP | SideBorder.RIGHT | SideBorder.BOTTOM));
  detailsSplitter.setFirstComponent(changeListPanel);
  detailsPanel=new GerritChangeDetailsPanel(project);
  changeListPanel.addListSelectionListener(new Consumer<ChangeInfo>(){
    @Override public void consume(    ChangeInfo changeInfo){
      changeSelected(changeInfo,project);
    }
  }
);
  JPanel details=detailsPanel.getComponent();
  details.setBorder(IdeBorderFactory.createBorder(SideBorder.TOP | SideBorder.RIGHT));
  detailsSplitter.setSecondComponent(details);
  Splitter horizontalSplitter=new Splitter(false,0.7f);
  horizontalSplitter.setShowDividerControls(true);
  horizontalSplitter.setFirstComponent(detailsSplitter);
  horizontalSplitter.setSecondComponent(repositoryChangesBrowser);
  panel.setContent(horizontalSplitter);
  reloadChanges(project,false);
  changeListPanel.showSetupHintWhenRequired(project);
  return panel;
}

Fixed version (ground truth):
public SimpleToolWindowPanel createToolWindowContent(final Project project){
  changeListPanel.setProject(project);
  diffManager.registerDiffTool(commentsDiffTool);
  SimpleToolWindowPanel panel=new SimpleToolWindowPanel(true,true);
  ActionToolbar toolbar=createToolbar(project);
  toolbar.setTargetComponent(changeListPanel);
  panel.setToolbar(toolbar.getComponent());
  RepositoryChangesBrowser repositoryChangesBrowser=repositoryChangesBrowserProvider.get(project,changeListPanel);
  Splitter detailsSplitter=new Splitter(true,0.6f);
  detailsSplitter.setShowDividerControls(true);
  changeListPanel.setBorder(IdeBorderFactory.createBorder(SideBorder.TOP | SideBorder.RIGHT | SideBorder.BOTTOM));
  detailsSplitter.setFirstComponent(changeListPanel);
  detailsPanel=new GerritChangeDetailsPanel(project);
  changeListPanel.addListSelectionListener(new Consumer<ChangeInfo>(){
    @Override public void consume(    ChangeInfo changeInfo){
      changeSelected(changeInfo,project);
    }
  }
);
  JPanel details=detailsPanel.getComponent();
  details.setBorder(IdeBorderFactory.createBorder(SideBorder.TOP | SideBorder.RIGHT));
  detailsSplitter.setSecondComponent(details);
  Splitter horizontalSplitter=new Splitter(false,0.7f);
  horizontalSplitter.setShowDividerControls(true);
  horizontalSplitter.setFirstComponent(detailsSplitter);
  horizontalSplitter.setSecondComponent(repositoryChangesBrowser);
  panel.setContent(horizontalSplitter);
  reloadChanges(project,false);
  changeListPanel.showSetupHintWhenRequired(project);
  return panel;
}