Don't make ItemManager a singleton

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/BaseItem.vala

@@ -133,7 +133,7 @@ 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);
+            ((ItemManager) get_ancestor (typeof (ItemManager))).move (this, val, 0);
             current_pos = val;
         });
 
@@ -284,7 +284,7 @@ public class Dock.BaseItem : Gtk.Box {
      * @param y pointer y position
      */
     public void calculate_dnd_move (BaseItem source, double x, double y) {
-        var launcher_manager = ItemManager.get_default ();
+        var launcher_manager = (ItemManager) get_ancestor (typeof (ItemManager));
 
         int target_index = launcher_manager.get_index_for_launcher (this);
         int source_index = launcher_manager.get_index_for_launcher (source);

src/DBus/ShellKeyGrabber.vala

@@ -59,6 +59,8 @@ public interface ShellKeyGrabber : GLib.Object {
 
     private static HashTable<uint, int> saved_action_ids;
 
+    private static Dock.ItemManager item_manager;
+
     public static void init () {
         settings = new Settings ("io.elementary.dock.keybindings");
         saved_action_ids = new HashTable<uint, int> (null, null);
@@ -71,6 +73,10 @@ public interface ShellKeyGrabber : GLib.Object {
         Bus.watch_name (BusType.SESSION, "org.gnome.Shell", BusNameWatcherFlags.NONE, () => on_watch.begin (), () => instance = null);
     }
 
+    public static void set_item_manager (Dock.ItemManager manager) {
+        item_manager = manager;
+    }
+
     private static async void on_watch () {
         try {
             instance = yield Bus.get_proxy (SESSION, "org.gnome.Shell", "/org/gnome/Shell");
@@ -109,7 +115,7 @@ public interface ShellKeyGrabber : GLib.Object {
             return;
         }
 
-        Dock.ItemManager.get_default ().launch (saved_action_ids[action]);
+        item_manager.launch (saved_action_ids[action]);
     }
 
     private static void ungrab_keybindings () requires (instance != null) {

src/ItemManager.vala

@@ -6,11 +6,6 @@
  public class Dock.ItemManager : Gtk.Fixed {
     private static Settings settings;
 
-    private static GLib.Once<ItemManager> instance;
-    public static unowned ItemManager get_default () {
-        return instance.once (() => { return new ItemManager (); });
-    }
-
     public Launcher? added_launcher { get; set; default = null; }
 
     private Adw.TimedAnimation resize_animation;
@@ -227,6 +222,7 @@
         if (item is Launcher) {
             launchers.add ((Launcher) item);
             sync_pinned ();
+            item.notify["pinned"].connect (sync_pinned);
         } else if (item is WorkspaceIconGroup) {
             icon_groups.add ((WorkspaceIconGroup) item);
         }

src/MainWindow.vala

@@ -20,6 +20,8 @@ public class Dock.MainWindow : Gtk.ApplicationWindow {
     private Settings transparency_settings;
     private static Settings settings = new Settings ("io.elementary.dock");
 
+    private ItemManager item_manager;
+
     private Pantheon.Desktop.Shell? desktop_shell;
     private Pantheon.Desktop.Panel? panel;
 
@@ -40,27 +42,26 @@ public class Dock.MainWindow : Gtk.ApplicationWindow {
         dock_box.append (new Container ());
         dock_box.append (new BottomMargin ());
 
-        unowned var launcher_manager = ItemManager.get_default ();
+        item_manager = new ItemManager ();
 
         // Don't clip launchers to dock background https://github.com/elementary/dock/issues/275
         var overlay = new Gtk.Overlay () {
             child = dock_box
         };
-        overlay.add_overlay (launcher_manager);
+        overlay.add_overlay (item_manager);
 
         var size_group = new Gtk.SizeGroup (Gtk.SizeGroupMode.BOTH);
         size_group.add_widget (dock_box);
-        size_group.add_widget (launcher_manager);
-
+        size_group.add_widget (item_manager);
         child = overlay;
 
         remove_css_class ("background");
 
         // Fixes DnD reordering of launchers failing on a very small line between two launchers
         var drop_target_launcher = new Gtk.DropTarget (typeof (Launcher), MOVE);
-        launcher_manager.add_controller (drop_target_launcher);
+        item_manager.add_controller (drop_target_launcher);
 
-        launcher_manager.realize.connect (init_panel);
+        item_manager.realize.connect (init_panel);
 
         settings.changed["autohide-mode"].connect (() => {
             if (panel != null) {
@@ -78,6 +79,8 @@ public class Dock.MainWindow : Gtk.ApplicationWindow {
         }
 
         window_drag_manager = new WindowDragManager (this);
+
+        ShellKeyGrabber.set_item_manager (item_manager);
     }
 
     private void update_transparency () {
@@ -112,7 +115,7 @@ public class Dock.MainWindow : Gtk.ApplicationWindow {
         surface.compute_size.connect ((surface, size) => {
             // manually set shadow width since the additional margin we add to avoid icons clipping when
             // bouncing isn't added by default and instead counts to the frame
-            var item_manager_width = ItemManager.get_default ().get_width ();
+            var item_manager_width = item_manager.get_width ();
             var shadow_size = (surface.width - item_manager_width) / 2;
             var top_margin = TOP_MARGIN + shadow_size - 1;
             size.set_shadow_width (shadow_size, shadow_size, top_margin, shadow_size);
@@ -121,7 +124,7 @@ public class Dock.MainWindow : Gtk.ApplicationWindow {
         surface.layout.connect ((surface, width, height) => {
             // manually set input region since container's shadow are is the content of the window
             // and it still gets window events
-            var item_manager_width = ItemManager.get_default ().get_width ();
+            var item_manager_width = item_manager.get_width ();
             var shadow_size = (width - item_manager_width) / 2;
             var top_margin = TOP_MARGIN + shadow_size;
             surface.set_input_region (new Cairo.Region.rectangle ({

src/WorkspaceSystem/IconGroup.vala

@@ -48,7 +48,8 @@ public class Dock.WorkspaceIconGroup : BaseIconGroup, WorkspaceItem {
 
     private void on_moving_changed () {
         if (!moving) {
-            workspace.reorder (ItemManager.get_default ().get_index_for_launcher (this));
+            var item_manager = (ItemManager) get_ancestor (typeof (ItemManager));
+            workspace.reorder (item_manager.get_index_for_launcher (this));
         }
     }