The 'In a new topic pane' invocation option causes the application plug-in or add-on related to the file (the Acrobat Reader in this example) to add a new instance of the topic pane.
Invocation option 'In a new topic pane'
You redisplayed the topic by clicking on the 'Back' navigation item on top of the topic pane as indicated by the red arrow in the next image.
Application file shown in a new topic pane
