I really would like to define the order of displayed bookmarks/objects in document and to have search field to filter them. The "content view" in comparison is not really necessary if you could sort things by line number.
Additionally displaying line numbers would be nice, too.
The "target in document" view doesn't allow any ordering or searching which makes it hard to find the right bookmarks etc. if you have many of them.
Finally, the navigator GUI seems to be a bit overloaded while some essential functions are missing and the "target in document" view is just an unordered list with no functions.
Any improvement would be nice!