@Override
 protected void buttonPressed(int buttonId) {
   if (buttonId == OK) {
     selectesCSSStylesClasses = cssClassComposite.getCSSStyleClasses();
   }
   super.buttonPressed(buttonId);
 }
 @Override
 protected Composite createControlComposite(Composite parent) {
   // Create down splitter container
   Split controlsContainer = new Split(parent, SWT.VERTICAL);
   controlsContainer.setLayout(new GridLayout());
   controlsContainer.setLayoutData(new GridData(GridData.FILL, GridData.FILL, true, true));
   cssClassComposite = createCSSClassComposite(controlsContainer);
   preview = createPreviewComposite(controlsContainer);
   cssClassComposite.addCSSClassSelectionChangedListener(preview);
   return controlsContainer;
 }