I looked, but I don't see a place to request features in future upgrades of Calibre. Here is my "problem" and the feature I would like to see added.
I "found" a lot of books when I wiped my kindle and sorted content on Calibre according to collections (I searched for Mystery tag, and moved the top 10 to my Kindle, etc.) That process, of browsing my Calibre library, convinced me I should do it more often. However, I can't tell what books are already on my Kindle. I have used tags to sort what I have read, but I was moving too many books to add an "on kindle" tag. When I connect my kindle, Calibre shows me which books are on the device. Is there any way of capturing that data, so I can disconnect my kindle and still know what is on it? Of course, Calibre could only show me what was on the kindle last time I hooked it up to Calibre.
There probably is a good reason why this can't be done, but I thought I would ask.