/**
 * Creates an individual diff viewer in the given composite.
 */
private void createDiffViewer(final FormToolkit toolkit, Composite composite,
    final TaskAttribute diffTaskAttribute) {

  int style = ExpandableComposite.TREE_NODE | ExpandableComposite.LEFT_TEXT_CLIENT_ALIGNMENT
      | ExpandableComposite.COMPACT;
  ExpandableComposite diffComposite = toolkit.createExpandableComposite(composite, style);
  diffComposite.clientVerticalSpacing = 0;
  diffComposite.setLayout(new GridLayout());
  diffComposite.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
  diffComposite.setTitleBarForeground(toolkit.getColors().getColor(IFormColors.TITLE));
  diffComposite.setText(calculateDiffChangeHeader(diffTaskAttribute));

  final Composite diffViewerComposite = toolkit.createComposite(diffComposite);
  diffComposite.setClient(diffViewerComposite);
  diffViewerComposite.setLayout(
      new FillWidthLayout(EditorUtil.getLayoutAdvisor(getTaskEditorPage()), 15, 0, 0, 3));

  diffComposite.addExpansionListener(new ExpansionAdapter() {
    @Override
    public void expansionStateChanged(ExpansionEvent event) {
      expandCollapseDiff(toolkit, diffViewerComposite, diffTaskAttribute, event.getState());
    }
  });
  GridDataFactory.fillDefaults().grab(true, false).applyTo(diffComposite);
}
 

/**
 * @param e
 */
protected void drawTitleBackground(PaintEvent e) {
	Rectangle bounds = getClientArea();
	label.setBackground(new Color[] {
			factory.getColors().getColor(IFormColors.H_GRADIENT_END),
			factory.getColors().getColor(IFormColors.H_GRADIENT_START) },
			new int[] { 100 }, true);
	Color bg = factory.getColors().getColor(IFormColors.H_GRADIENT_END);
	Color gbg = factory.getColors().getColor(IFormColors.H_GRADIENT_START);
	GC gc = e.gc;
	gc.setForeground(bg);
	gc.setBackground(gbg);
	gc.fillGradientRectangle(bounds.x, bounds.y, bounds.width,
			bounds.height, true);
	// background bottom separator
	gc.setForeground(factory.getColors().getColor(
			IFormColors.H_BOTTOM_KEYLINE1));
	gc.drawLine(bounds.x, bounds.height - 2, bounds.x + bounds.width - 1,
			bounds.height - 2);
	gc.setForeground(factory.getColors().getColor(
			IFormColors.H_BOTTOM_KEYLINE2));
	gc.drawLine(bounds.x, bounds.height - 1, bounds.x + bounds.width - 1,
			bounds.height - 1);
}
 

@Override
public void createControl(Composite parent, final FormToolkit toolkit) {
  final List<TaskAttribute> diffTaskAttributes = getDiffTaskAttributes();

  if (diffTaskAttributes == null || diffTaskAttributes.isEmpty()) {
    return;
  }
  int style = ExpandableComposite.TWISTIE | ExpandableComposite.SHORT_TITLE_BAR;
  final Section groupSection = toolkit.createSection(parent, style);
  groupSection.setText("Changes (" + diffTaskAttributes.size() + ')');
  groupSection.clientVerticalSpacing = 0;
  groupSection.setForeground(toolkit.getColors().getColor(IFormColors.TITLE));

  if (groupSection.isExpanded()) {
    addDiffViewersToSection(toolkit, diffTaskAttributes, groupSection);
  } else {
    groupSection.addExpansionListener(new ExpansionAdapter() {
      @Override
      public void expansionStateChanged(ExpansionEvent e) {
        if (groupSection.getClient() == null) {
          try {
            getTaskEditorPage().setReflow(false);
            addDiffViewersToSection(toolkit, diffTaskAttributes, groupSection);
          } finally {
            getTaskEditorPage().setReflow(true);
          }
          getTaskEditorPage().reflow();
        }
      }
    });
  }
}
 

public void resetSectionToolBarColors() {
	TabbedPropertySheetWidgetFactory f = new TabbedPropertySheetWidgetFactory();
	FormColors defaultColors = f.getColors();
	defaultColors.initializeSectionToolBarColors();

	FormColors colors = factory.getColors();
	colors.createColor(IFormColors.H_GRADIENT_START, defaultColors.getColor(IFormColors.H_GRADIENT_START).getRGB());
	colors.createColor(IFormColors.H_GRADIENT_END, defaultColors.getColor(IFormColors.H_GRADIENT_END).getRGB());
	colors.createColor(IFormColors.H_BOTTOM_KEYLINE1,
			defaultColors.getColor(IFormColors.H_BOTTOM_KEYLINE1).getRGB());
	colors.createColor(IFormColors.H_BOTTOM_KEYLINE2,
			defaultColors.getColor(IFormColors.H_BOTTOM_KEYLINE2).getRGB());
}
 

private void createPersonLabel(Composite parent, Image image, String text) {
	Label imageLabel = new Label(parent, 0);
	imageLabel.setImage(image);
	Label textLabel = this.toolkit.createLabel(parent, text);
	textLabel.setForeground(this.toolkit.getColors().getColor(IFormColors.TB_TOGGLE));
}
 

public void applyStyles(TextStyle textStyle) {
	textStyle.foreground = new FormToolkit(Display.getDefault()).getColors().getColor(IFormColors.TB_TOGGLE);
	if (textStyle instanceof StyleRange) {
		((StyleRange) textStyle).fontStyle = SWT.ITALIC;
	}
}
 

public TabbedPropertyTitleCssPropertyHandler() {
	cssPropertyToSWTProperty.put(BOTTOM_KEYLINE_1, IFormColors.H_BOTTOM_KEYLINE1);
	cssPropertyToSWTProperty.put(BOTTOM_KEYLINE_2, IFormColors.H_BOTTOM_KEYLINE2);
	cssPropertyToSWTProperty.put(GRADIENT_START, IFormColors.H_GRADIENT_START);
	cssPropertyToSWTProperty.put(GRADIENT_END, IFormColors.H_GRADIENT_END);
}
 

/**
 * Constructor for TabbedPropertyTitle.
 *
 * @param parent
 *            the parent composite.
 * @param factory
 *            the widget factory for the tabbed property sheet
 */
public TabbedPropertyTitle(Composite parent,
		TabbedPropertySheetWidgetFactory factory) {
	super(parent, SWT.NO_FOCUS);
	this.factory = factory;

	this.addPaintListener(e -> {
			if (image == null && (text == null || text.equals(BLANK))) {
				label.setVisible(false);
			} else {
				label.setVisible(true);
			}
			drawTitleBackground(e);
	});

	factory.getColors().initializeSectionToolBarColors();
	setBackground(factory.getColors().getBackground());
	setForeground(factory.getColors().getForeground());

	FormLayout layout = new FormLayout();
	layout.marginWidth = 1;
	layout.marginHeight = 2;
	setLayout(layout);

	Font font;
	if (! JFaceResources.getFontRegistry().hasValueFor(TITLE_FONT)) {
		FontData[] fontData = JFaceResources.getFontRegistry().getBold(
				JFaceResources.DEFAULT_FONT).getFontData();
		/* title font is 2pt larger than that used in the tabs. */
		fontData[0].setHeight(fontData[0].getHeight() + 2);
		JFaceResources.getFontRegistry().put(TITLE_FONT, fontData);
	}
	font = JFaceResources.getFont(TITLE_FONT);

	label = factory.createCLabel(this, BLANK);
	label.setBackground(new Color[] {
			factory.getColors().getColor(IFormColors.H_GRADIENT_END),
			factory.getColors().getColor(IFormColors.H_GRADIENT_START) },
			new int[] { 100 }, true);
	label.setFont(font);
	label.setForeground(factory.getColors().getColor(IFormColors.TITLE));
	FormData data = new FormData();
	data.left = new FormAttachment(0, 0);
	data.top = new FormAttachment(0, 0);
	data.right = new FormAttachment(100, 0);
	data.bottom = new FormAttachment(100, 0);
	label.setLayoutData(data);

	/*
	 * setImage(PlatformUI.getWorkbench().getSharedImages().getImage(
	 * ISharedImages.IMG_OBJ_ELEMENT));
	 */
}