There's a super convenient search field at Collection level, in the top bar above the list of collection items.

For 2 main use cases:

1. If you're dealing with a high volume of records, and have defined a predictable ID for each, it's super convenient to just type the IS of the record you're looking for instead of browsing an endless list. For example I have records with ID such as "FP-2018-12-13", FP being a code for a type of record. Super convenient.
2. same as above but acts as a filter: Just type FP in the search field and get a filtered list of all records with the searched term
   

Those two examples already work at Collection level. That would be great to have an area on the right for when none of the collections are selected yet (making the Collections label at the top clickable for that), and be able to search within all the collections.