[crane3]

If you click/select a cover in the cover display mode, you should see the outline for what is allocated for each cover/picture. I think the size/scaling depends on the 'resolution' of the cover & how it fits into the allocated space when scaled up. Having said that, I have a couple of covers that did not scale well as the resolutions were less than ??/180; then the one with a real cover is the front page of an AVR manual that is in pdf.

I don't see a "problem" as it is like a line of text is either word wrapped or not. Visually, I would like to see a graphic cover fill the space as much as possible without distortion. On a TV, there is a difference in presentation of 'full screen' & 'adjusted/anamophic' (?) where the picture is either distorted to fill a screen or having parts of the picture cut off.

The only 'cure' is to select or adjust each cover's resolution to be the same size; I think adjusting the cover picture is too much work for me as I rather that downloaded cover is what it is supposed to be & accommodated for the book.

I have win10 & a LG 4k monitor; I do not use the LG's monitor driver as had found that win10 had/has a conflict under some situations in the scaling of what I was viewing.

edit mode: In the cover mode, you can also see the resolution display when moving the arrow to the detail at the right side & hover with the arrow. Looks to be nice for comparing the 'full size' & smaller size cover resolutions which will help to change the cover sizes if so desired.