In the DP1, it looks like one case was not taken into account in Finder.app when it comes to Dark Mode support:
Custom background for disk images (or folders).
Because if you have a custom white background, then the white label used for files/folders in Icon view is not going to be very legible.
Is there a plan to improve this?
Or is there a plan to support HEIC images for the custom background of folders/disk images like for the Desktop Wallpaper?
Please file a bug report on this, especially if you have a case where it is particularly problematic. The sooner the better in terms of being able to make an impact
Bug Report filed.