Display invisible selected items in some lists

The lists are:
-> List of events (in the event handler)
-> List of documents (in all "enablement" dialogs)
-> User permissions (in "enablement" dialogs)

It is impossible to see at a first sight if 1 or more items are selected in these list, except it the item is in the first 4-5 rows. So, you spend time scrolling the lists to check if a row is highlighted ot not.

Having an informative area giving the list of selected items, if any, whould help a lot when looking at the configuration. See the screenshot for a raw, basic idea