Navigate to the Offline view (accessed via Other Views of the home screen). In this view, you can define filters ensuring that all important objects are accessible even without a network connection.
Example: You can define all the documents of a certain project to always be available – even when no network connection is available. Just start creating a new filter, press the Define filter... button and add your project as a property filter.
To remove the offline filter, select Remove from the filter context menu.