How to highlight help topic in ToC

Hello,

I want to have a Robohelp generated output help topic highlighted in the left-side ToC (when the help topic is accessed from the application), as seen in the below screenshot. This seems to be an app integration functionality, i.e., this seems to have to do with the way the help file is integrated with the application it is for. Does anyone know what developer script allows this? Thank you very much.