In folder, especially with loads of pictures, it would be very helpfull to change the view of the files from "detailed" to "thumbnail" or "preview / slideshow" function of the first page or picture that is marked.

For pictures, to identify the right one for fast access, and to spare bandwith (e.g. on travel using phone), it would be of great benefit if it was possible to watch a picture like e.g. in Windows Explorer.

This will of come in handy in other cases as well, but for pictures, which represents significantly larger files in Bytes than documents, it would save alot of time if it was possible to see a small preview or thumbnail of the picture before opening it (or the index page of a document) to make it faster to choose the right document.

Normally documents is easy to find, as long as they have a proper naming according to a structure predefined, but there is also times where this is not possible and a thumbnail / preview functionality would be very helpful.