The UI could use one simple tweak to make it more effective and efficient:
Add a simple option to Auto sort (like chests have now) by:
Line 1 - Class or Racial Abilities (Backstab, Action Surge, Turn Undead, Tadpole abilities, etc.)
Line 2+ - Spells driven by spellslots ordered by level (cantrip, 1st, 2nd, etc.)
Line 3+ - Scrolls and spells/powers driven by magic items
Line 4 - Potions
Line 5 - usable items (throwables etc.)
This would clean up the UI a lot and could act as a "clean up" function when abilities begin to be scattered across multiple lines and finding them is an exercise in Finding Waldo.