When creating a dashboard panel, e.g. showing the active repositories, and limiting it to number smaller than the number of visible repositories, e.g. 5 on our instance, Phabricator will display the specified number of repositories (e.g. 5), but show no indication that more repositories are available.
Proposed solution: If more results are available than can be shown, add a "See more" / "Show more" link at the bottom. (This would be similar to the list of rooms in Conpherence.)
This affects at least following panels: Tasks, Repositories, Commits, but I assume all are affected and a generalised solution is possible that can also be used in e.g. the Conpherence room list.