private void createSelectedListBox(Composite parent) {
    selectedListBox = new List(parent, SWT.MULTI | SWT.H_SCROLL | SWT.V_SCROLL | SWT.BORDER);
    selectedListBox.addSelectionListener(
        new SelectionListener() {
          public void widgetDefaultSelected(SelectionEvent event) {}

          public void widgetSelected(SelectionEvent event) {

            if (selectedListBox.getSelectionCount() > 0) setRemoveButtonEnabled(true);
            else setRemoveButtonEnabled(false);
            return;
          }
        });

    GridData gd = new GridData(GridData.FILL_BOTH);
    gd.widthHint = SIZING_LISTS_WIDTH;
    gd.heightHint = SIZING_LISTS_HEIGHT;
    selectedListBox.setLayoutData(gd);
  }
  private void createSourceViewer(Composite parent) {
    sourceFileViewer =
        new TreeViewer(new Tree(parent, SWT.MULTI | SWT.H_SCROLL | SWT.V_SCROLL | SWT.BORDER));
    sourceFileViewer.setContentProvider(new WorkbenchContentProvider());
    sourceFileViewer.setLabelProvider(new WorkbenchLabelProvider());
    sourceFileViewer.addSelectionChangedListener(
        new ISelectionChangedListener() {
          public void selectionChanged(SelectionChangedEvent event) {
            java.util.List list;
            ISelection selection = event.getSelection();
            boolean newFilesSelected = false;

            if (selection instanceof IStructuredSelection) {
              list = ((IStructuredSelection) selection).toList();
              for (Iterator i = list.iterator(); i.hasNext(); ) {
                IResource resource = (IResource) i.next();
                if (resource instanceof IFile) {
                  if (checkIfFileInTarget((IFile) resource) == false) newFilesSelected = true;
                }
              }
              setAddButtonEnabled(newFilesSelected);
            }
          }
        });
    sourceFileViewer.addDoubleClickListener(
        new IDoubleClickListener() {
          public void doubleClick(DoubleClickEvent event) {
            addSelectedFilesToTargetList();
          }
        });

    Control treeWidget = sourceFileViewer.getTree();
    GridData gd = new GridData(GridData.FILL_BOTH);
    gd.widthHint = SIZING_LISTS_WIDTH;
    gd.heightHint = SIZING_LISTS_HEIGHT;
    treeWidget.setLayoutData(gd);
  }