use haskell-gi bugfix to improve tab reordering

.gitignore

@@ -3,9 +3,10 @@ cabal.project.local
 
 assets/*.svg
 assets/*/
-refs/
-img/examples
 files/
+img/examples
+math/
+refs/
 
 *.txt
 *.md

cabal.project

@@ -29,3 +29,9 @@ source-repository-package
   type: git
   location: https://github.com/sheaf/waargonaut
   tag: dc835fb86d2592fa2e55753fa4eb7c59d6124699
+
+-- haskell-gi: add fix for GValue
+source-repository-package
+  type: git
+  location: https://github.com/haskell-gi/haskell-gi
+  tag: 6fe7fc271095b5b6115b142f72995ebc11840afb

src/app/MetaBrush/UI/FileBar.hs

@@ -18,6 +18,8 @@ import Control.Monad
   ( join, unless, void )
 import Data.Foldable
   ( for_, sequenceA_ )
+import Data.Functor
+  ( (<&>) )
 import Data.Traversable
   ( for )
 
@@ -32,6 +34,10 @@ import qualified GI.Cairo.Render.Connector as Cairo
 -- gi-gtk
 import qualified GI.Gtk as GTK
 
+-- haskell-gi-base
+import qualified Data.GI.Base.GValue as GI
+import qualified Data.GI.Base.GType  as GI
+
 -- stm
 import qualified Control.Concurrent.STM      as STM
   ( atomically )
@@ -134,7 +140,7 @@ newFileTab
     widgetAddClasses closeFileButton [ "fileBarCloseButton" ]
     GTK.widgetShowAll tab
 
-    -- We've placed the new tab at the end. Now rearrange it if needed.
+    -- We've placed the new tab at the end. Now rearrange it if necessary.
     case newTabLoc of
       LastTab -> pure ()
       AfterCurrentTab -> do
@@ -143,13 +149,10 @@ newFileTab
           for mbUnique \ docUnique -> do
             Map.lookup docUnique <$> STM.readTVar fileBarTabsTVar
         for_ mbActiveTab \ ( activeTab, _ ) -> do
-          children <- GTK.containerGetChildren fileTabsBox
-          for_ ( zip children [0..] ) \ ( childWidget, activeTabIndex ) -> do
-            mbBox <- GTK.castTo GTK.Box childWidget
-            for_ mbBox \ box ->
-              if box == activeTab
-              then GTK.boxReorderChild fileTabsBox tab ( activeTabIndex + 1 )
-              else pure ()
+          gValue <- GI.newGValue GI.gtypeInt
+          GTK.containerChildGetProperty fileTabsBox activeTab "position" gValue
+          ( GI.get_int gValue <&> ( +1 ) ) >>= GI.set_int gValue
+          GTK.containerChildSetProperty fileTabsBox       tab "position" gValue
 
     -- Ensure consistency of hover/selection state between the two elements in the tab.
     for_ @_ @_ @_ @() [ Exists @GTK.IsWidget pgButton, Exists @GTK.IsWidget closeFileButton ] \ ( Exists button ) -> do