Program: 52029
Project: 52029
Buggy source:
public void layout(){
  double totalFlex=0.0;
  for (  XulComponent comp : children) {
    if (comp.getManagedObject() == null) {
      continue;
    }
    if (comp.getFlex() > 0) {
      flexLayout=true;
      totalFlex+=comp.getFlex();
    }
  }
  if (flexLayout)   gc.fill=GridBagConstraints.BOTH;
  double currentFlexTotal=0.0;
  for (int i=0; i < children.size(); i++) {
    XulComponent comp=children.get(i);
    if (comp instanceof XulSplitter) {
      JPanel prevContainer=container;
      container=new JPanel(new GridBagLayout());
      final JSplitPane splitter=new JSplitPane((this.getOrientation() == Orient.VERTICAL) ? JSplitPane.VERTICAL_SPLIT : JSplitPane.HORIZONTAL_SPLIT,prevContainer,container);
      splitter.setContinuousLayout(true);
      final double splitterSize=currentFlexTotal / totalFlex;
      splitter.setResizeWeight(splitterSize);
      if (totalFlex > 0) {
        splitter.addComponentListener(new ComponentListener(){
          public void componentHidden(          ComponentEvent arg0){
          }
          public void componentMoved(          ComponentEvent arg0){
          }
          public void componentShown(          ComponentEvent arg0){
          }
          public void componentResized(          ComponentEvent arg0){
            splitter.setDividerLocation(splitterSize);
            splitter.removeComponentListener(this);
          }
        }
);
      }
      if (!flexLayout) {
        if (this.getOrientation() == Orient.VERTICAL) {
          gc.weighty=1.0;
        }
 else {
          gc.weightx=1.0;
        }
        prevContainer.add(Box.createGlue(),gc);
      }
      managedObject=splitter;
    }
    Object maybeComponent=comp.getManagedObject();
    if (maybeComponent == null || !(maybeComponent instanceof Component)) {
      continue;
    }
    if (this.getOrientation() == Orient.VERTICAL) {
      gc.gridheight=comp.getFlex() + 1;
      gc.gridwidth=GridBagConstraints.REMAINDER;
      gc.weighty=(totalFlex == 0) ? 0 : (comp.getFlex() / totalFlex);
    }
 else {
      gc.gridwidth=comp.getFlex() + 1;
      gc.gridheight=GridBagConstraints.REMAINDER;
      gc.weightx=(totalFlex == 0) ? 0 : (comp.getFlex() / totalFlex);
    }
    currentFlexTotal+=comp.getFlex();
    Component component=(Component)maybeComponent;
    container.add(component,gc);
    if (i + 1 == children.size() && !flexLayout) {
      if (this.getOrientation() == Orient.VERTICAL) {
        gc.weighty=1.0;
      }
 else {
        gc.weightx=1.0;
      }
      container.add(Box.createGlue(),gc);
    }
  }
}

Fixed version (ground truth):
public void layout(){
  double totalFlex=0.0;
  for (  XulComponent comp : children) {
    if (comp.getManagedObject() == null) {
      continue;
    }
    if (comp.getFlex() > 0) {
      flexLayout=true;
      totalFlex+=comp.getFlex();
    }
  }
  if (flexLayout)   gc.fill=GridBagConstraints.BOTH;
  double currentFlexTotal=0.0;
  for (int i=0; i < children.size(); i++) {
    XulComponent comp=children.get(i);
    if (comp instanceof XulSplitter) {
      JPanel prevContainer=container;
      container=new ScrollablePanel(new GridBagLayout());
      JScrollPane leftScroll=new JScrollPane(prevContainer);
      leftScroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_NEVER);
      leftScroll.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
      final JSplitPane splitter=new JSplitPane((this.getOrientation() == Orient.VERTICAL) ? JSplitPane.VERTICAL_SPLIT : JSplitPane.HORIZONTAL_SPLIT,leftScroll,container);
      splitter.setContinuousLayout(true);
      final double splitterSize=currentFlexTotal / totalFlex;
      splitter.setResizeWeight(splitterSize);
      if (totalFlex > 0) {
        splitter.addComponentListener(new ComponentListener(){
          public void componentHidden(          ComponentEvent arg0){
          }
          public void componentMoved(          ComponentEvent arg0){
          }
          public void componentShown(          ComponentEvent arg0){
          }
          public void componentResized(          ComponentEvent arg0){
            splitter.setDividerLocation(splitterSize);
            splitter.removeComponentListener(this);
          }
        }
);
      }
      if (!flexLayout) {
        if (this.getOrientation() == Orient.VERTICAL) {
          gc.weighty=1.0;
        }
 else {
          gc.weightx=1.0;
        }
        prevContainer.add(Box.createGlue(),gc);
      }
      managedObject=splitter;
    }
    Object maybeComponent=comp.getManagedObject();
    if (maybeComponent == null || !(maybeComponent instanceof Component)) {
      continue;
    }
    if (this.getOrientation() == Orient.VERTICAL) {
      gc.gridheight=comp.getFlex() + 1;
      gc.gridwidth=GridBagConstraints.REMAINDER;
      gc.weighty=(totalFlex == 0) ? 0 : (comp.getFlex() / totalFlex);
    }
 else {
      gc.gridwidth=comp.getFlex() + 1;
      gc.gridheight=GridBagConstraints.REMAINDER;
      gc.weightx=(totalFlex == 0) ? 0 : (comp.getFlex() / totalFlex);
    }
    currentFlexTotal+=comp.getFlex();
    Component component=(Component)maybeComponent;
    container.add(component,gc);
    if (i + 1 == children.size() && !flexLayout) {
      if (this.getOrientation() == Orient.VERTICAL) {
        gc.weighty=1.0;
      }
 else {
        gc.weightx=1.0;
      }
      container.add(Box.createGlue(),gc);
    }
  }
}