[FR] Jump to next selected item

[kylehase]

Feature request for a way to jump to the next selected item. This is most useful when using "Select Custom" on a very large set and want to review each of the items selected before deletion. It would work akin to how "next" works when using ctrl+f on other apps.

Another related feature would be for the scrollbar to indicate the position of selected items, similar to how most browsers do with ctrl+f.