I too would like improvements to the image viewer. I understand that improvements to the game details pane are being considered, where it will be able to show all images associated with a game and not just the fan art and screenshots. I would suggest that either the game details pane and/or the image viewer should have some sort of method of showing the user at a glance which images are available and letting them select the one they want to see - rather than having to scroll through an arbitrary list, as one currently has to do in both the image viewer and the game details pane.
The nesting feature is excellent and I’ve experienced no issues with it so far. It does however open up a great opportunity to leverage more info and metadata about the platform category, platform or playlist. I know that you can add “notes” to playlists and platform categories, and can also add some more details to the platforms - but this info is somewhat tucked away with the user having to “edit” to access it (unless you are in BigBox where the platform details can be shown). It would be great if in Launchbox, the user had the ability to display information, images and a platform video (or platform category or playlist video) when selecting the corresponding platform, platform category or playlist. For example, the user could select “Nintendo Entertainment System” under consoles and be presented with information, images and a video relating to the NES. This could for example be shown in the main window, with the games list(s) below the platform. Hope this description is clear!