Allow dropping items by dragging off inventory

src/Dodge/DisplayInventory.hs

@@ -172,7 +172,7 @@ filterSectionsPair endstr filtfn itms filtdescription mfilt =
     , itms'
     )
   where
-    filtsis = fromMaybe mempty $ do
+    filtsis = fold $ do
         str <- mfilt
         return $
             IM.singleton