Button browseButton = new Button(composite, SWT.PUSH);
browseButton.setText("Browse ...");
browseButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(SelectionEvent e) {
ElementTreeSelectionDialog dialog = new ElementTreeSelectionDialog(getShell(),
new WorkbenchLabelProvider(), new WorkbenchContentProvider());
dialog.setTitle("Select descriptor");
dialog.setMessage("Select descriptor");
dialog.setInput(ResourcesPlugin.getWorkspace().getRoot());
dialog.setInitialSelection(ResourcesPlugin.getWorkspace().getRoot().
findMember(typeSystemText.getText()));