[gui] Use actual path of files and not their prettified versions.

src/plugins/gui/file_manager.ml

@@ -23,7 +23,7 @@
 let add_files (host_window: Design.main_window_extension_points) =
   Gtk_helper.source_files_chooser
     (host_window :> Gtk_helper.source_files_chooser_host)
-    (List.map Filepath.Normalized.to_pretty_string (Kernel.Files.get ()))
+    (Kernel.Files.get () :> string list)
     (fun filenames ->
        Kernel.Files.set (List.map Datatype.Filepath.of_string filenames);
        if Ast.is_computed () then