it means that a book is not needed in the device any more so I can delete it, but then again I want to have a flag that it is not a book that has never seen my device yet.
So take this for example: You purchase a book, add it to the library. Attach a reader to computer and it shows that the book is not in the device. You upload it and now it has green checkbox to show that the book is copied into the reader. Once you finish reading the book (all the way through), you remove the book from the reader. Now you have no way of knowing wether this book is already read or not.
This may not be important if you keep up with one device, but me and my wife both have our own readers and I do not keep up with all the romance books she reads, so for me it is very hard to know which books I need her to have on her device. Browsing through unread books is little bit hard for her since the covers of Harlequin books all look the same
I have solved my problem like so: I have createted two new columns that are type of checkobox: Finished by me, Finished by her and now I have the feature I was looking for. Now I can delete all read books from the readers and keep only unread books in them
