Split every tab in two panes

src/Termonad/Types.hs

@@ -25,6 +25,8 @@ import GI.Gtk
   , notebookGetNthPage
   , notebookGetNPages
   )
+import qualified GI.Gtk as Gtk
+import Data.GI.Base.GObject
 import GI.Pango (FontDescription)
 import GI.Vte (Terminal, CursorBlinkMode(..))
 import Text.Pretty.Simple (pPrint)
@@ -530,6 +532,23 @@ data TMStateInvariantErr
   | TabsDoNotMatch TabsDoNotMatch
   deriving Show
 
+printWidgetTree :: Gtk.IsWidget a => a -> IO ()
+printWidgetTree widget_ = do
+  widget <- Gtk.toWidget widget_
+  go "" widget
+  where
+    go :: Text -> Gtk.Widget -> IO ()
+    go indent w = do
+      type_ <- gtypeFromInstance w
+      name <- Gtk.gtypeName type_
+      let ptr = Gtk.managedForeignPtr . Gtk.toManagedPtr $ w
+      putStrLn $ indent <> pack name <> "  " <> pack (show ptr)
+      maybeContainer <- Gtk.castTo Gtk.Container w
+      for_ maybeContainer $ \container -> do
+        children <- Gtk.containerGetChildren container
+        for_ children $ \child -> do
+          go ("  " <> indent) child
+
 -- | Gather up the invariants for 'TMState' and return them as a list.
 --
 -- If no invariants have been violated, then this function should return an