Can't set item position without selecting an item.

It doesn't seem possible to set the item position on any screen without selecting some item. If you select <none>, then it won't let you set the item position. It can be problematic when you're setting the position, for, say, a special item room in a dungeon.

Yeah, I too think it's ridiculous that it brings up the item list every time you set the item position. Same happens when you click the combo flag tool on the toolbar, as it always brings up the combo flag list, so that you can't scroll through the combo flags with the mouse wheel or whatever, without having to select a flag from the list first.

Thing is though, it was most likely intentional.

Actually, I've found that once your item is set you can just click on it and drag it around.