Add some comments

Author: jeremypw

src/Dialogs/PreferencesDialog.vala

@@ -144,7 +144,7 @@ public class Scratch.Dialogs.Preferences : Granite.Dialog {
         main_box.add (stackswitcher);
         main_box.add (stack);
 
-        plugins.hook_preferences_dialog (this);
+        plugins.hook_preferences_dialog (this); // Unused?
 
         if (plugins.get_n_plugins () > 0) {
             var pbox = plugins.get_view ();

src/Services/PluginManager.vala

@@ -162,7 +162,10 @@ namespace Scratch.Services {
 
             // Bind the engine ListModel and use a row factory
             list_box.bind_model (engine, get_widget_for_plugin_info);
-            //Cannot sort a ListModel so sort the ListBox (is there a better way?)
+            // Cannot sort a ListModel so sort the ListBox (is there a better way?)
+            // Gtk warns the function will be ignored but it does in fact work, at least
+            // on initial display. We know the model will not change while the view is used
+            // In Gtk4 could use SortListModel
             list_box.set_sort_func ((r1, r2) => {
                 return strcmp (
                     r1.get_child ().get_data<string> ("name"),