Use ListModels

src/AppSystem/App.vala

@@ -103,7 +103,6 @@ public class Dock.App : Object {
 
         notify["pinned"].connect (() => {
             check_remove ();
-            ItemManager.get_default ().sync_pinned ();
         });
 
         WindowSystem.get_default ().notify["active-workspace"].connect (() => {

src/AppSystem/AppSystem.vala

@@ -15,13 +15,17 @@ public class Dock.AppSystem : Object, UnityClient {
         return instance.once (() => { return new AppSystem (); });
     }
 
-    public signal void app_added (App app);
+    private ListStore apps_store;
+    public ListModel apps { get { return apps_store; } }
 
     private GLib.HashTable<unowned string, App> id_to_app;
 
     private AppSystem () { }
 
     construct {
+        apps_store = new ListStore (typeof (App));
+        apps_store.items_changed.connect (save_pinned);
+
         id_to_app = new HashTable<unowned string, App> (str_hash, str_equal);
     }
 
@@ -41,12 +45,46 @@ public class Dock.AppSystem : Object, UnityClient {
 
     private App add_app (DesktopAppInfo app_info, bool pinned) {
         var app = new App (app_info, pinned);
+        app.removed.connect (remove_app);
+        app.notify["pinned"].connect (save_pinned);
         id_to_app[app_info.get_id ()] = app;
-        app.removed.connect ((_app) => id_to_app.remove (_app.app_info.get_id ()));
-        app_added (app);
+        apps_store.append (app);
         return app;
     }
 
+    private void remove_app (App app) {
+        id_to_app.remove (app.app_info.get_id ());
+
+        uint pos;
+        if (apps_store.find (app, out pos)) {
+            apps_store.remove (pos);
+        }
+    }
+
+    public void reorder_app (App app, uint new_index) {
+        uint pos;
+        if (!apps_store.find (app, out pos)) {
+            warning ("Tried to reorder an app that is not in the store");
+            return;
+        }
+
+        apps_store.remove (pos);
+        apps_store.insert (new_index, app);
+    }
+
+    private void save_pinned () {
+        string[] new_pinned_ids = {};
+
+        for (uint i = 0; i < apps_store.get_n_items (); i++) {
+            var app = (App) apps_store.get_item (i);
+            if (app.pinned) {
+                new_pinned_ids += app.app_info.get_id ();
+            }
+        }
+
+        settings.set_strv ("launchers", new_pinned_ids);
+    }
+
     public async void sync_windows () {
         var windows = WindowSystem.get_default ().windows;
 
@@ -79,20 +117,20 @@ public class Dock.AppSystem : Object, UnityClient {
         }
     }
 
-    public void add_app_for_id (string app_id) {
+    public App? add_app_for_id (string app_id) {
         if (app_id in id_to_app) {
             id_to_app[app_id].pinned = true;
-            return;
+            return id_to_app[app_id];
         }
 
         var app_info = new DesktopAppInfo (app_id);
 
         if (app_info == null) {
             warning ("App not found: %s", app_id);
-            return;
+            return null;
         }
 
-        add_app (app_info, true);
+        return add_app (app_info, true);
     }
 
     public void remove_app_by_id (string app_id) {

src/AppSystem/Background/BackgroundItem.vala

@@ -6,10 +6,10 @@
  */
 
 public class Dock.BackgroundItem : BaseIconGroup {
-    public signal void apps_appeared ();
+    private ListStore group_store;
+    public ListModel group_model { get { return group_store; } }
 
     public BackgroundMonitor monitor { private get; construct; }
-    public bool has_apps { get { return monitor.background_apps.get_n_items () > 0; } }
 
     private Gtk.Popover popover;
 
@@ -20,11 +20,13 @@ public class Dock.BackgroundItem : BaseIconGroup {
             icons: new Gtk.MapListModel (background_monitor.background_apps, (app) => {
                 return ((BackgroundApp) app).icon;
             }),
-            disallow_dnd: true
+            group: Group.NONE
         );
     }
 
     construct {
+        group_store = new ListStore (typeof (BackgroundItem));
+
         var list_box = new Gtk.ListBox () {
             selection_mode = BROWSE
         };
@@ -53,9 +55,9 @@ public class Dock.BackgroundItem : BaseIconGroup {
         monitor.background_apps.items_changed.connect ((pos, n_removed, n_added) => {
             if (monitor.background_apps.get_n_items () == 0) {
                 popover.popdown ();
-                removed ();
+                group_store.remove (0);
             } else if (n_removed == 0 && n_added != 0 && n_added == monitor.background_apps.get_n_items ()) {
-                apps_appeared ();
+                group_store.append (this);
             }
         });
 

src/AppSystem/Launcher.vala

@@ -148,7 +148,6 @@ public class Dock.Launcher : BaseItem {
         });
 
         app.launched.connect (animate_launch);
-        app.removed.connect (() => removed ());
 
         var bounce_animation_target = new Adw.CallbackAnimationTarget ((val) => {
             var height = overlay.get_height ();

src/BaseItem.vala

@@ -11,6 +11,7 @@ public class Dock.BaseItem : Gtk.Box {
     }
 
     public enum Group {
+        NONE,
         LAUNCHER,
         WORKSPACE
     }
@@ -21,10 +22,8 @@ public class Dock.BaseItem : Gtk.Box {
         dock_settings = new GLib.Settings ("io.elementary.dock");
     }
 
-    public signal void removed ();
     public signal void revealed_done ();
 
-    public bool disallow_dnd { get; construct; default = false; }
     /**
      * The group in the dock this item belongs to. This is used to allow DND
      * only within that group.
@@ -133,7 +132,7 @@ public class Dock.BaseItem : Gtk.Box {
         reveal.done.connect (set_revealed_finish);
 
         var animation_target = new Adw.CallbackAnimationTarget ((val) => {
-            ItemManager.get_default ().move (this, val, 0);
+            ((Gtk.Fixed) parent).move (this, val, 0);
             current_pos = val;
         });
 
@@ -155,17 +154,17 @@ public class Dock.BaseItem : Gtk.Box {
         gesture_click = new Gtk.GestureClick ();
         add_controller (gesture_click);
 
+        if (group == NONE) {
+            return;
+        }
+
         var drop_target = new Gtk.DropTarget (typeof (BaseItem), MOVE) {
             preload = true
         };
         add_controller (drop_target);
         drop_target.enter.connect (on_drop_enter);
         drop_target.drop.connect (on_drop);
 
-        if (disallow_dnd) {
-            return;
-        }
-
         var drag_source = new Gtk.DragSource () {
             actions = MOVE
         };
@@ -181,6 +180,11 @@ public class Dock.BaseItem : Gtk.Box {
         popover_tooltip.dispose ();
     }
 
+    public uint get_index () {
+        var item_group = get_ancestor (typeof (ItemGroup)) as ItemGroup;
+        return item_group?.get_index_for_item (this) ?? Gtk.INVALID_LIST_POSITION;
+    }
+
     public void set_revealed (bool revealed) {
         fade.skip ();
         reveal.skip ();
@@ -219,6 +223,10 @@ public class Dock.BaseItem : Gtk.Box {
      * when moving a launcher so that its current_pos is always up to date.
      */
     public void animate_move (double new_position) {
+        if (timed_animation.value_to == new_position) {
+            return;
+        }
+
         timed_animation.value_from = current_pos;
         timed_animation.value_to = new_position;
 
@@ -285,15 +293,7 @@ public class Dock.BaseItem : Gtk.Box {
      */
     public void calculate_dnd_move (BaseItem source, double x, double y) {
         var launcher_manager = ItemManager.get_default ();
-
-        int target_index = launcher_manager.get_index_for_launcher (this);
-        int source_index = launcher_manager.get_index_for_launcher (source);
-
-        if (source_index == target_index) {
-            return;
-        }
-
-        launcher_manager.move_launcher_after (source, target_index);
+        launcher_manager.move_launcher_after (source, (int) get_index ());
     }
 
     private bool on_drop (Value val) {
@@ -306,7 +306,7 @@ public class Dock.BaseItem : Gtk.Box {
 
     private bool is_allowed_drop (Value val) {
         var obj = val.get_object ();
-        return obj != null && obj is BaseItem && ((BaseItem) obj).group == group;
+        return obj != null && obj is BaseItem && ((BaseItem) obj).group == group && obj != this;
     }
 
     private class PopoverTooltip : Gtk.Popover {