Add Left/Right key functionality for the keyboard with posts that are in pools. The mouse is rather hard to use in the left hand.
-1 on this.
Use the existing keybinds a/d instead, left/right are too useful for scrolling sideways if the image is larger than window (common if you are not in 'scale to fit' mode).
(theoretically the arrows should already do this though, per the keyboard shortcut cheatsheet)