This is how I preview film emulations. I don’t know why the down arrow does nothing for you, Mark - it works for me and does not require that I keep the mouse cursor on the Rendering box; it only requires that selecting a film emulation be the last operation I performed. (The arrow keys will continue to control and adjust whatever you last selected until you select something else or undo a different operation.)
I use DxO software on Windows 10. When I use the up and down arrow keys to change a setting, I see the results immediately.
I’ve created 9 partial presets, which only change the film type, as an initial test. It only took around 10 minutes to create all 9 of them. They are very small, only 660+ bytes each. They work on my desktop, but I will copy them to my laptop to test there as well. Can’t do anymore right now, but the effort is much smaller than I thought it would be. Once I have finished and tested everything I will zip them up and make them available, at no cost, to whoever would like them, including DXO.
Instead of scrolling through them one by one to see the effect of each on your image, you can view the general affect of each film type in the preset previews, visually compare them, and directly select the one you prefer. Yes, some of the film types may be more difficult to choose on the small preset previews (that’s true of almost all preset previews), but we can still get a general idea how each one differs without having to scroll from a list. I think presets would allow us to select a film type faster and act as a memory jogger in future editing sessions. It doesn’t replace the other method, it just adds additional flexibility.
I’ve finished creating the FilmPack partial presets for PhotoLab. I just need to do more comprehensive testing before I’m ready to make them available to others. DXO had already created 39 color and b&w Filmpack Designer presets for PhotoLab. I created an additional 82 film presets representing all the FilmPack film types as well as the 5 Generic film types already included in PhotoLab, Of course for them to work, Filmpack has to be installed.