[gthumb-list] Disabling EXIF thumbnails?

[Derek Chen-Becker <derek chen-becker org>]

I have photos spanning back quite a ways (and several cameras). One of
my older cameras saves a very low-res thumbnail (180x180) in EXIF, while
my preference in gThumb is set for 256x256. The result is that images
taken from that camera are quite blurry/artifacted in thumbnail view. I
have plenty of disk to store generated thumbnails, so is there any way
to disable reading thumbnails from EXIF and just force generation?

Thanks,

Derek