protected void forceExistingChecked(CheckStateChangedEvent event) {
   if (fExisting != null) {
     Object elem = event.getElement();
     if (fExisting.contains(elem)) {
       fViewer.setChecked(elem, true);
     }
   }
 }
 protected void newFolderButtonPressed() {
   Object createdFolder = createFolder(fSelectedContainer);
   if (createdFolder != null) {
     CheckboxTreeViewer treeViewer = fViewer;
     treeViewer.refresh(fSelectedContainer);
     treeViewer.reveal(createdFolder);
     treeViewer.setChecked(createdFolder, true);
     treeViewer.setSelection(new StructuredSelection(createdFolder));
     updateOKStatus();
   }
 }