Allow dropping items by dragging off inventory

src/Dodge/Item/Draw.hs

@@ -3,11 +3,11 @@ module Dodge.Item.Draw (
     itemEquipPict,
 ) where
 
+import Data.Foldable
 import Dodge.Data.ComposedItem
 import Dodge.Data.DoubleTree
 import Geometry.Data
 import Control.Lens
-import Data.Maybe
 import Dodge.Creature.HandPos
 import Dodge.Data.Creature
 import Dodge.Item.Draw.SPic
@@ -19,7 +19,7 @@ itemEquipPict cr itmtree = case itm ^. itUse of
     UseHeld{} | itm ^? itLocation . ilIsRoot == Just True 
             && itm ^? itLocation . ilIsSelected == Just True
         -> overPosSP (heldItemOffset itm cr) (itemTreeSPic itmtree)
-    ituse -> fromMaybe mempty $ do
+    ituse -> fold $ do
         attachpos <- ituse ^? uequipEffect . eeAttachPos
         i <- itm ^? itLocation . ilInvID
         epos <- cr ^? crInvEquipped . ix i