Launcher: new context option to close all windows

src/DesktopIntegration.vala

@@ -25,4 +25,5 @@ public interface Dock.DesktopIntegration : GLib.Object {
     public abstract async Window[] get_windows () throws GLib.DBusError, GLib.IOError;
     public abstract async void show_windows_for (string app_id) throws GLib.DBusError, GLib.IOError;
     public abstract async void focus_window (uint64 uid) throws GLib.DBusError, GLib.IOError;
+    public abstract async void close_window (uint64 uid) throws GLib.DBusError, GLib.IOError;
 }

src/Launcher.vala

@@ -259,6 +259,8 @@ public class Dock.Launcher : Gtk.Box {
         app.notify["running"].connect (update_running_revealer);
         update_running_revealer ();
 
+        app.notify["running"].connect(close_all_instances);
+
         var drop_target_file = new Gtk.DropTarget (typeof (File), COPY);
         add_controller (drop_target_file);
 
@@ -336,6 +338,31 @@ public class Dock.Launcher : Gtk.Box {
         }
     }
 
+    private void close_all_instances(){
+        if (app.running) {
+            if (app.action_group.lookup_action("close-instances") != null) {
+                return;
+            }
+
+            var close_item = new GLib.MenuItem(_("Close All Windows"), "app-actions.close-instances");
+            app.menu_model.append_item(close_item);
+
+            var close_action = new SimpleAction("close-instances", null);
+            close_action.activate.connect(() => {
+                var desktop_integration = LauncherManager.get_default().desktop_integration;
+
+                foreach (var win in app.windows) {
+                    desktop_integration.close_window.begin(win.uid, null);
+                }
+
+                app.windows.clear(); 
+            });
+
+            close_action.set_enabled(true);
+            app.action_group.add_action(close_action);
+        }
+    }
+
     private void animate_launch () {
         if (bounce_up.state == PLAYING || bounce_down.state == PLAYING) {
             return;