GTK: fix closing tabs via [Control]+w when tab was switched

src/HSFM/GUI/Gtk/MyGUI.hs

@@ -45,7 +45,6 @@ import Paths_hsfm
 -- |Set up the GUI. This only creates the permanent widgets.
 createMyGUI :: IO MyGUI
 createMyGUI = do
-
   let settings' = MkFMSettings False True 24
   settings <- newTVarIO settings'
   operationBuffer <- newTVarIO None
@@ -85,6 +84,10 @@ createMyGUI = do
   notebook          <- builderGetObject builder castToNotebook
                        "notebook"
 
+  -- this is required so that hotkeys work as expected, because
+  -- we then can connect to signals from `viewBox` more reliably
+  widgetSetCanFocus notebook False
+
   -- construct the gui object
   let menubar = MkMenuBar {..}
   let fprop = MkFilePropertyGrid {..}