I need an image viewer capable of showing thumbs for folders, but showing only the thumb of the first image in each folder, not thumbs with a mix of images in those folders, like the Windows Explorer is showing. If possible, would be awesome if the viewer would allow me to set for each folder which image in that folder would be shown as the thumb of that folder (instead of the first image in the folder) and to save that configuration in a configuration file, so I can use it on another computer too. Would be very nice if the viewer would allow em to set the size of the thumbs (all thumbs the same size, of course).
If possible, I am looking for a free viewer capable of doing this.
I remember I've found such a viewer some years ago but I can't remember it's name now. I think it was a viewer that was available for Linux and MacOS too.