add app icon, file list menu control

readme.md

@@ -12,11 +12,15 @@ So, what comes before Z? Y.
 
 This is being created to scratch an itch for me and only me.
 
+## Image credit
+
+Generated via <https://gopherize.me/gopher/ab6a409adff6140f25080835e82384f25bfe15c5>. Renee French designed the original Gopher; see <https://go.dev/blog/gopher> for his history.
+
 ## TODO
 
-* image resizing
-* file sorting options
-* display a list of filenames
-* skip file load if direction key is repeated
-* cache loaded files for quick back-and-forth
-* preload next file for performance
+[ ] image resizing
+[ ] file sorting options
+[x] display a list of filenames
+[ ] skip file load if direction key is repeated
+[ ] cache loaded files for quick back-and-forth
+[ ] preload next file for performance