New tab when editing groups

When editing a node or a group in Node-RED in the top right corner there are different tabs, like for example: properties, environment variables and description. Changing between them is done by clicking the icons in the top right corner. I would like to add an additional icon for some security options when editing a group (a grouping of nodes). But i can't seem to find how to add these tabs and where to find the html for them. Any ideas?