I find the file list to be the weakest part of the OctoPrint ui. The widet is barely 290x490 pixels yet it's contents have huge amounts of padding making only 4 files visible at a time.
I would like to see whole folder structures that you can expand and collapse. The action buttons don't need to be next to every file but can be at the bottom and refer to the selected file. It's also currently confusing how to view files on the SD card so why not just add that to the view also?
So I did a quick mockup design in Photoshop. I haven't reduced the total size of the widget, there is actually less space here for each file yet you can see so much more and get a better overview for all your files.
How hard would it be to make a plugin that replaces the original list with this?