Editing AZW3 book adds 1x1 pixel gray gif each time
Every time I edit and save an AZW3 ebook, it apparently adds a 1x1 pixel gray gif image. Using Calibre version 1.21 in both Windows 7 and 8.1.
The first time there are none, and using Check Book (F7) only reports the thumbnail cover image as being "not referenced", which is fine.
However, if I edit it, save it, and edit it again, there is a second unreferenced image, a 1x1 pixel gray gif file. If I do it again and again, I get a third, fourth, fifth, etc.
On another note, I love the Edit Book feature! I made an extra donation to Calibre just because you added this wonderful tool!
Thanks so much for the work you do!