code: public void handleBrowseRootFolder() {
  		DirectoryDialog dialog = new DirectoryDialog (getShell());
  		String platform = SWT.getPlatform();
  		dialog.setFilterPath (platform.equals("win32") || platform.equals("wpf") ? "c:\\" : "/");
  
  		String foldername = dialog.open();
  		System.err.println("RESULT ROOT_FOLDER = " + foldername);
  		rootFolderText.setText(foldername);		
  	}
docs: Uses the standard container selection dialog to choose the new value for
  the container field.