code: protected INode chooseType(INode[] types, String title)
  	{
  		try
  		{
  			DebugTypeSelectionDialog mmsd = new DebugTypeSelectionDialog(VdmDebugPlugin.getActiveWorkbenchShell(), types, title, project);
  			if (mmsd.open() == Window.OK)
  			{
  				return (INode) mmsd.getResult()[0];
  			}
  		} catch (Exception e)
  		{
  			e.printStackTrace();
  		}
  
  		return null;
  	}
docs: Prompts the user to select a type from the given types.
  
  @param types
  the types to choose from
  @param title
  the selection dialog title
  @return the selected type or <code>null</code> if none.