Moved to Photoshop forum.
Is there a way to have maximize compatibility disabled and at the same time be able to use previews with QuickLook?
QL relies on a compatibility image in a layered PSD (a single non-Background layer is still a layered document), although if the PSD contains only the special Background layer then that will be used by QL. Maximize Compatibility results in a compatibility composite in the PSD, otherwise a solid white compatibility image is embedded and that's what you see in QL.
OK, thanks. I thought it wouldn't be possible. Too bad
QL can be extended but an extension would need to understand the many layer types and layer effects supported by PSD in order to build a composite. I think the only program that currently does that fully is Photoshop CS6 itself.