Context menu event when multiple files are selected

When a file or folder in the Files pane is right clicked, a context menu appears. This event can be captured by using registerEvent("file-menu", delegate)).


What I want to achieve is to add a menu item to the context menu whenever multiple items in the Files pane are selected using Alt+Click and the user right clicks. Currently, only two items are visible for me in this menu, “Move x items to…” and “Delete”.


Unfortunately the file-menu event is not triggered in this scenario and I could not find anything related to this in the documentation. How can I capture this event, and the related information such as which files/folders were selected when the user right clicked?