This adds an easy way to get back to the preconfigured location.
While Folder View reverts to the start location automatically when a popup closes, if you use it in a sidebar, this can never happen and leaves you with tediously clicking "Back" continuously.

The button is shown when:

• The title label is shown (ie. not in cascading popups on the desktop)
• and the currently viewed at location is not the configured (start) location