GTK: improve history navigation

* increase maximum numbers of items in the history
* empty the "forward" history if we enter a directory
  via normal navigation

src/HSFM/GUI/Gtk/Callbacks.hs

@@ -464,7 +464,7 @@ goDir :: MyGUI -> MyView -> Item -> IO ()
 goDir mygui myview item = do
   cdir <- getCurrentDir myview
   modifyTVarIO (history myview)
-    (\(p, n) -> (path cdir `addHistory` p, n))
+    (\(p, _) -> (path cdir `addHistory` p, []))
   refreshView' mygui myview item
 
 

src/HSFM/GUI/Gtk/Utils.hs

@@ -157,5 +157,5 @@ addHistory i xs
   | length xs == maxLength = i : take (maxLength - 1) xs
   | otherwise              = i : xs
   where
-    maxLength = 5
+    maxLength = 10