Hi, I've been playing with this a bit and here's what I've seen - this is very consistent.
The first time I use Find Duplicates the Reset Quick Search button does not work. The first click on the button seems to do nothing, the second click clears the entire library and I have to use the Virtual Library -> Additional Restriction -> None menu option to get my library back to visible. The next time and any subsequent time I use Find Duplicates, I can clear the search, and return to my library using the Reset Quick Search Button. The behavior is reset when I quit and restart Calibre.
Now here's the interesting (at least to me) part...if I start Calibre and go right to Virtual Library -> Additional Restriction -> None then do a Find Duplicates, I can use the Reset Quick Search button to clear the search. So, I believe the newer release of Calibre has made the virtual library restrictions stick where they were cleared in the past. I'm not sure if that's right, but if it is, maybe Calibre could open with the additional restrictions set to none and it would work all the time.
At any rate, I've gotten quite used to doing it either way and now that I understand it, it's not really as big a hassle as I thought it would be. Thanks to everyone involved for writing these excellent programs - I'm only posting in case it helps, but honestly, I'm very happy with what I have and I'm almost done clearing out my dupes, I've kept a few for testing purposes at this point.
