Currently, sidebar edition plug-ins work best with smaller documents. If you've used Acrolinx classic edition, then you are accustomed to certain features which might not be available in the sidebar edition. For example, check selection and recheck selection allow you to use Acrolinx with longer documents.
We're planning to improve the sidebar integrations by supporting more real-time checking. Features like 'check selection' and 'recheck selection' that you are familiar with in Acrolinx classic edition will become less important. Instead, Acrolinx will check for you at regular intervals, for example, after you've made changes to a specific paragraph. That way, you'll know if the paragraph that you changed meets your quality standards.