For me the most confusing thing about inventory is how the windows display.
I only noticed by accident that I could drag the windows and place them next to each other.

With that sudden realisation using the inventory windows became a bit more intuitive. I think if you have two inv open they should tile automatically. Also the inventory of the current character needs to be highlighted (e.g. a gold border like the character button). The amount of times I've right clicked on an inventory item to use it only to get frustrated that it didn't work (because the other character was active!) is beyond counting now.

I'd also like more keyboard shortcuts.

The tutorial says something about CTRL-clicking on an enemy to see its effects. I never got that working. I'd like a way to select an enemy character (portrait) so I can then hover over the effects on it to see what they do.

I'd like F1-Fx to select a character in order from top. (Currently seems to try and cast my first spell)

I'd like SHIFT and CTRL modifiers to bring up the other 2 toolbars. So SHIFT-1 casts spell one on toolbar two. Maybe also have Shift-UP and Shift-Down cycle the toolbars.

I like that I can now cast spells using the character (and enemy) portraits. What's missing is some way of just hitting them. E.g. if I CTRL or ALT click on a portrait it just tries to whack that enemy with their weapon (It should show projected movement if I over over the portrait with the modifier pressed).

I'd like a quick way to move stuff between characters. Manually dragging gets really annoying quickly. Maybe allow multi-select or modifier like ALT-Left-Click to send to other character (get's trickier if you have more than 2, I know, will need some thought).

I'd like a visual indication if placing two thing over each other will do something. I like the experimenting to see what stuff does, but after dozens of items just swapping places in my inventory I got fed up with it and just sold everything.

I'd like more options for ALT. E.g. show containers, highlight NPCs (and their names), usable objects, items that can be picked up; it seems a bit inconsistent at the moment. I think this could all be done with a single outline, or with different colours maybe, and possibly options as to what's shown. (For Ironman mode, is there such a thing?, maybe disable ALT completely smile )