HELP! Pressing Up/B doesn't do anything in the inventory!
Maybe it isn't fully clear from the controls.
You can grab an object in the inventory (the legend in the inventory should change). While the item is grabbed you can move it to another place or delete it. Using the keyboard you would grab/release an object using the SPACE key. The gameboys B key is mapped to LEFT SHIFT. So to delete an object you would simply press LEFT SHIFT.
Hope this helps :)