Allow selection of noncontiguous items using shift

ghcidOutput

@@ -1 +1 @@
-All good (594 modules, at 17:16:08)
+All good (594 modules, at 18:13:44)

src/Dodge/Inventory/Swap.hs

@@ -17,7 +17,6 @@ import qualified IntMapHelp as IM
 import Dodge.Data.World
 import Control.Monad
 
--- can be specialised for when we know that item i is selected
 swapInvItems ::
     (Int -> IM.IntMap (SelectionItem ()) -> Maybe Int) ->
     Int ->

src/Dodge/Update/Input/InGame.hs

@@ -139,16 +139,22 @@ updateMouseReleaseInGame w = case w ^. input . mouseContext of
     OverInvDrag k mpos _ _ -> 
         input . mouseContext .~ MouseInGame $
         fromMaybe w $ tryDropSelected mpos w <|> tryPickupSelected k mpos w
+    OverInvDragSelect ssel mesel | ScancodeLShift `M.member` (w ^. input . pressedKeys)
+        -> w & input . mouseContext .~ MouseInGame
+            & hud . hudElement . diSelection . _Just . _3 %~ getuniques
+                (maybe mempty (h ssel) (mesel ^? _Just . _2))
+                -- note this assumes that mesel isn't outside the first
+                -- selection, this should perhaps just be made impossible by
+                -- removing the first part of the tuple
     OverInvDragSelect _ Nothing ->
         w & input . mouseContext .~ MouseInGame
             & hud . hudElement . diSelection . _Just . _3 %~ const mempty
     OverInvDragSelect ssel (Just esel) ->
         w & input . mouseContext .~ MouseInGame
---            & hud . hudElement . diSelectionExtra
---                .~ h ssel (snd esel) -- IM.keysSet  [min (snd ssel) (snd esel) + 1 .. max (snd ssel) (snd esel)]
             & augInvDirectSelect (f (min ssel esel) (h ssel (snd esel)))
     _ -> w
   where
+    getuniques x y = IS.union x y IS.\\ IS.intersection x y
     f (x,y) z = (x,y,z)
     h (k,i) j = fold $ do
         sss <- w ^? hud . hudElement . diSections . ix k . ssItems
@@ -164,6 +170,8 @@ updateMouseClickInGame cfig w = case w ^. input . mouseContext of
         return $
             w & input . mouseContext
                 .~ OverInvDragSelect ysel Nothing
+    OverInvSelect x | ScancodeLShift `M.member` (w ^. input . pressedKeys )
+        -> w & input . mouseContext .~ OverInvDragSelect x (Just x)
     OverInvSelect x -> startDrag x cfig w
     OverTerminalReturn tmid -> terminalReturnEffect tmid w
     OverTerminalEscape ->