Comment 8 for bug 890441

what I call "in use" is like interacting with it rather than letting it "sit there"

the ubuntu-bug collecting job added that list to the bug:
https://launchpadlibrarian.net/85141332/usr_lib_nautilus.txt

which is the packages you have installed which add a .so to the nautilus directory

so that seems to not be coherent with your comments...

to reply to your other question, no, leaks are not especially a nautilus bug, they can be due to third party softwares which install some .so loaded by nautilus, leaks in those would show in the nautilus process since that's where they are loaded, the 3 packages listed in comment #6 do install a such .so and could be causing the issue (the other ones in the list of the file I listed as well but those are installed by default and would affect all users where your issue is not something most users notice)