Because of that and some of the undesirable idiosyncracies of grids compared to map objects, I have replaced the inventory and spell list with visual grids, seen here:

The bottom panel is called "Knowledge" because it's a combination of magic and active class skills (of which there are none so far), though I think I'm going to split them up.
In keeping with the idea that you should be able to play this game without a mouse, you can cycle through your items by pressing plus or minus. The same will be true of spells, with tab flipping between them.
The blank space above inventory is still the action panel, which as previously described gives some info on the object/character/whatever that is currently selected, and then lists the available actions (if any) along with a number that can be used to activate it with a single keypress. Once I add room descriptions and generic actions to the game, it will never be blank as it appears here.
There are still some other odd missing pieces of the interface that make it cumbersome to actually play at the moment, but I expect to start hosting the game again within the next few days.